The Natural Philosopher wrote:

I think my longest up on XP without a crash is 3 hours.

Seriously, three hours? What on earth were you doing to it?
I ran XP for 7 years( fair enough it was switched off each night and
restarted the next day) and only once saw a BSOD.

Have ran 7 for four years now (also did my HNC in Networking in it),
it has never blue screened. There is one program (A game. Which runs
fine on XP [youngest son now has the XP machine]) it refuses to run
have tried (halfheartedly) to get to the bottom of this but have pretty
much chalked it down to 'one of those things'.