RedHat Installation Problem - No USB

Installing Red Hat Enterprise Linux v.4 from CDs

I'm installing Linux on my old desktop for holiday activity. Thought it would be straight forward, but was I wrong!

After my disaster first attempt, I had a second go using all the default options, as I did the first time.
This time using a 20G IDE hard-drive instead of a 4G one.

Everything looked ok until I inserted a USB thumb drive.
It won?t show my USB drive anywhere.
(In my first installation it appeared on the desktop as NO_NAME when I insert the drive. It also showed as ?/dev/sda1? in running df & mount).

I?ve ran both the ?df? and ?mount? comments but the device ?/dev/sda1? did not appear.

All you Linux experts out there please tell me;

What could be the problem?

What can I do without re-install the OS?

PS: Using Pentium 3, 20G IDE hard-drive and 384M RAM.