This is a good utility that tells you how long your computer has been running. And its free.
http://www.idyle.com/uptime/
The only time my system is unstable is when I play dx7 games I have also experienced lock ups with SMP in Q3A. I also wanna be leet and post my PC so here it goes.
dual p3 500 @ 560
soyo D6IBA w/7880 SCSI
320 megs of PC133
geforce CL 256 DDR
CL Live Value
8 gig IBM (OS)
18 gig IBM (pr0n)
DVD, CD-R yada yada yada...
and intel says I need more?