If your computer has Win95 on it, chances are Xp won't run on it.
Hit Microsofts web page to check on minimum specs, and also look up your hardware to see if it's supported.
Xp has a pretty high requirement, especially compared to Win95. I personally can't stand to run XP on anything lower then a 500mhz p2 or higher with 256meg of ram minimum on that kinda of system. Anything lower I find dogs like hell with WinXP.
Also remember XP takes 1-1.5gigs for the install, a lot of older Win95 PC's only had 1-2gig hdd's.
Scope it out