temperature sounds ok,maybe a wee bit on the high side but nothing that would cause the system to crash.under 50C for the cpu and under 30C for the case temps are optimal but it depends on your room temps to start with.
what temp does it reach if running a game or cpu intensive program etc for a while? a good cpu stabillity tester is prime95 click here and run a torture test for a few hours,that should heat things up a bit(its not actually designed for this but works very well)
next time you get a BSOD note down the error code and do a search on click here or into the search box click here should give some clues to the problem.my guess is its maybe a driver issue or xp might need an update click here
aida32 will give all sorts of info from system temps to links to driver updates for your system and loads more click here