Goto: http://www.crucial.com or http://www.kingston.com and check for specs as well and see if they have some available. Older Dell's used RDRAM which is NOT SDRAM. Plus, in some cases, Dell ECC type ram and you will need to know that for the best match to your system. One or the other websites supplied will check to see what ram you do have via online.
I found at the Dell site, 256MB PC100 168 DIMM RAM stick. I see the same specs at other sites for PC100 SDRAM. WILL THE SDRAM WORK OR WHAT? THANKS