Problem installing Red Hat Linux 3 on Acer Aspire 4520

Hi,

I have the following Acer Specs:-

AMD 64 X2 Processor Athlon TK53 (1.7GHz, 2 x 256KB Cache)
* 1024MB DDR2 533MHz Memory (1GB RAM)
* 160GB Toshiba Hard Disk Drive (5400RPM)
* 8X DVD WRITER DVD-Super Multi double-layer drive (Also Writes 8.5 GB DVDs)
* 14.1" WXGA TFT LCD High brightness (200 nits), 1280 x 800 resolution with 16ms response time
* Integrated Bluetooth 2.0+EDR (Enhanced Data Rate) Bluetooth Inbuilt
* Gigabit LAN (10/100/1000 Compatible)
* 6 Cell Lithium Ion Battery
* Integrated 802.11 b/g Wireless LAN (WIFI)
* 56K Fax Modem, 4 USB 2.0 Ports
* Integrated 5-in-1 Card Reader & S-Video TV Out,Consumer IR Port
* Nvidia GeForce 7000M GS Upto 1GB of TurboCache

During installation of RHEL3 Update 4 , it says "No hard Disk found" , I cannot proceed
Pls help