How might I install a proprietary driver?

I got another tower yesterday -- my other one died. System>Admin>Hardware Drivers says I have no proprietary drivers. Normally (for me, in the past), it would give me the option to install a NVIDIA accelerated graphics driver version 96; but not now. I'm running K/Ubuntu 9.04 and Firefox 3.0; 3.5.3. Here are my specs:

randall-desktop
    description: Computer
    width: 32 bits
  *-core
       description: Motherboard
       physical id: 0
     *-memory
          description: System memory
          physical id: 0
          size: 511MiB
     *-cpu:0
          product: Pentium III (Coppermine)
          vendor: Intel Corp.
          physical id: 1
          bus info: cpu@0
          version: 6.8.6
          size: 1GHz
          width: 32 bits
          capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic
 sep mtrr pge mca cmov pat pse36 mmx fxsr sse
        *-cache:0
             description: L1 cache
             physical id: 0
: size: 32KiB
        *-cache:1
             description: L2 cache
             physical id: 1
             size: 256KiB
     *-cpu:1
          product: Pentium III (Coppermine)
          vendor: Intel Corp.
          physical id: 2
          bus info: cpu@1
          version: 6.8.6
          size: 1GHz
          width: 32 bits
          capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse
        *-cache:0
             description: L1 cache
             physical id: 0
             size: 32KiB
        *-cache:1
             description: L2 cache
: physical id: 1
             size: 256KiB
     *-pci
          description: Host bridge
          product: 82840 840 [Carmel] Chipset Host Bridge (Hub A)
          vendor: Intel Corporation
          physical id: 100
          bus info: pci@0000:00:00.0
          version: 01
          width: 32 bits
          clock: 33MHz
          configuration: driver=agpgart-intel module=intel_agp
        *-pci:0
             description: PCI bridge
             product: 82840 840 [Carmel] Chipset AGP Bridge
             vendor: Intel Corporation
             physical id: 1
             bus info: pci@0000:00:01.0
             version: 01
             width: 32 bits
             clock: 66MHz
: capabilities: pci bus_master
           *-display UNCLAIMED
                description: VGA compatible controller
                product: NV5 [RIVA TNT2/TNT2 Pro]
                vendor: nVidia Corporation
                physical id: 0
                bus info: pci@0000:01:00.0
                version: 11
                width: 32 bits
                clock: 66MHz
                capabilities: bus_master cap_list
                configuration: latency=64 maxlatency=1 mingnt=5
        *-pci:1
             description: PCI bridge
             product: 82801AA PCI Bridge
             vendor: Intel Corporation
             physical id: 1e
             bus info: pci@0000:00:1e.0
             version: 02
             width: 32 bits
             clock: 33MHz
: capabilities: pci bus_master
           *-network:0
                description: Ethernet interface
                product: 82557/8/9/0/1 Ethernet Pro 100
                vendor: Intel Corporation
                physical id: 2
                bus info: pci@0000:02:02.0
                logical name: eth2
                version: 08
                serial: 00:02:a5:37:53:a2
                width: 32 bits
                clock: 33MHz
                capabilities: bus_master cap_list ethernet physical
                configuration: broadcast=yes driver=e100 driverversion=3.5.23-k6-NAPI firmware=N/A ip=98.28.109.233 latency=66 maxlatency=56 mingnt=8 module=e100 multicast=yes
           *-scsi
                description: SCSI storage controller
                product: AIC-7892P U160/m
                vendor: Adaptec
                physical id: 7
: bus info: pci@0000:02:07.0
                logical name: scsi2
                version: 02
                width: 64 bits
                clock: 66MHz
                capabilities: scsi bus_master cap_list scsi-host
                configuration: driver=aic7xxx latency=64 maxlatency=25 mingnt=40 module=aic7xxx
           *-network:1
                description: Ethernet interface
                product: 3c905C-TX/TX-M [Tornado]
                vendor: 3Com Corporation
                physical id: 9
                bus info: pci@0000:02:09.0
                logical name: eth3
                version: 30
                serial: 00:01:03:e0:66:80
                width: 32 bits
                clock: 33MHz
                capabilities: bus_master cap_list ethernet physical
                configuration: broadcast=yes driver=3c59x latency=64 maxlatency=:
10 mingnt=10 module=3c59x multicast=yes
        *-isa
             description: ISA bridge
             product: 82801AA ISA Bridge (LPC)
             vendor: Intel Corporation
             physical id: 1f
             bus info: pci@0000:00:1f.0
             version: 02
             width: 32 bits
             clock: 33MHz
             capabilities: isa bus_master
             configuration: latency=0
        *-ide
             description: IDE interface
             product: 82801AA IDE Controller
             vendor: Intel Corporation
             physical id: 1f.1
             bus info: pci@0000:00:1f.1
             logical name: scsi0
             version: 02
             width: 32 bits
: clock: 33MHz
             capabilities: ide bus_master emulated
             configuration: driver=ata_piix latency=0
           *-cdrom
                description: SCSI CD-ROM
                physical id: 0.0.0
                bus info: scsi@0:0.0.0
                logical name: /dev/cdrom2
                logical name: /dev/scd0
                logical name: /dev/sr0
                capabilities: audio
                configuration: status=nodisc
        *-usb
             description: USB Controller
             product: 82801AA USB Controller
             vendor: Intel Corporation
             physical id: 1f.2
             bus info: pci@0000:00:1f.2
             version: 02
             width: 32 bits
             clock: 33MHz
: capabilities: bus_master
             configuration: driver=uhci_hcd latency=0 module=uhci_hcd
        *-serial UNCLAIMED
             description: SMBus
             product: 82801AA SMBus Controller
             vendor: Intel Corporation
             physical id: 1f.3
             bus info: pci@0000:00:1f.3
             version: 02
             width: 32 bits
             clock: 33MHz
             configuration: latency=0
        *-multimedia
             description: Multimedia audio controller
             product: 82801AA AC'97 Audio Controller
             vendor: Intel Corporation
             physical id: 1f.5
             bus info: pci@0000:00:1f.5
             version: 02
             width: 32 bits
             clock: 33MHz
: capabilities: bus_master
             configuration: driver=Intel ICH latency=0 module=snd_intel8x0
  *-network DISABLED
       description: Ethernet interface
       physical id: 1
       logical name: pan0
       serial: 72:73:fd:a1:4e:a8
       capabilities: ethernet physical
       configuration: broadcast=yes driver=bridge driverversion=2.3 firmware=N/A multicast=yes
(END)