How about a little more information.
 
What linux distro and version number are you using?
 
Are you "hotplugging" the stick, or is it in the usb port when you boot into the distro?
 
Has the stick been re-formatted, or does it have it's original factory formatting?
 
Is this the only usb device plugged into the computer?

you should need no driver other than the generic usbstorage module you already have.
 
have you run 'fdisk /dev/sda' to have a look at the device's partition table ?
(don't make any changes!)
.. in case it's like a zip drive which puts the vfat filesystem on /dev/sda4 ?
 

Which distro are you using. The older ones would require manual mounting whereas the newer ones don't. Download usbview and chec if your drive is detected in the 1st place.

That's where I was going to go. On some distros, you even have to modprobe the module...
 
modprobe usb-storage
 
Then I check dmesg to see if it recognized the stick, then mount it at that device.
 
It can get a little more complicated, if you have another usb device attached, say a multi-card flash reader.

i am using redhat 9 (2.4).
in same machine it works on win2k.
 

This is where posting as much information on the subject is helpful. Redhat 9, not RedHat 9.1...
 
Is this USB stick USB 1.0 or 2.0 compliant?
 
Is the port that you are mounting the stick in USB 1.0 or 2.0?
 
Are you using a USB port attached to the motherboard (primary port) or an add-on card?
 
See a discussion on the subject here.
 
Did you try to modprobe usb-storage by going to a terminal window as root user?
 
It sounds like you have some experience with Linux, but let us know if you need clarification on my questions.