RedHat Installation Problem - No USB

Installing Red Hat Enterprise Linux v.4 from CDs

This is the second time I installed Red Hat using all the default options, as I did the first time.
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.)
I?ve tried both the ?df? and ?mount? comments but the device ?/dev/sda1? did not appear.

Linux experts please tell me;

What could be the problem?

What can I do to fix this problem without re-install the OS?

Using Platinum 3, 20G IDE hard-drive and 256M RAM.