Are the computer device drivers required to install ubuntu 11.04

Device drivers for most hardware are built into Ubuntu, and you do not generally need to install them. Furthermore, if you did have the device drivers CD for your computer, it would probably be useless for Ubuntu or any other Linux-based operating system anyway, since it would probably provide Windows drivers, and it is not usually possible to run Windows drivers on a non-Windows operating system.

I recommend booting from the Ubuntu 11.04 live CD/DVD or live USB stick and selecting Try Ubuntu (rather than Install Ubuntu), and seeing if it works with your hardware. If there are some devices that do not work out of the box, it might still be possible for you to get them working, but at least you will be prepared. Conversely, it is possible that things will work fine from the live CD/DVD/USB but then not work on the installed system, but that is quite unlikely. Testing it out first is pretty much always a good preparatory step before installing. A live system will run slower than an installed system, especially if running from a CD/DVD, but other than that it should give you some sense of what the system will be like.

It depends upon the devices you have. Most devices are supported out-of-the-box, but not all.

card reader and webcams are usually OK,
wlan is more often a problem, but drivers can be installed.
DVD will read out of the box, but you will not be able to decrypt dvds without decryption software, which you must explicitly install (not included by default for legal reasons).

your best bet is to run a liveCD, which will simply read the OS directly from a CD/USB, without touching your hard drive -- you can remove the CD/USB and reboot and everything will be restored to normal. Devices that function normally will continue to do so when you install. Problematic devices will be easily identified -- just test each function you want to use.

To make a liveCD/USB, have a look at this:

https://help.ubuntu.com/community/LiveCD