Even then most of the time your computer will shut down before it does any serious damage really, overclocking these days is pretty much foolproof.
EDIT: I agree get a decent CPU cooler, I used to recomend the Artic Freezer 7 but i'm ****ed at them becuase they went from 29.99 to 69.99!!!!!! They are a good cooler but **** not that good!
E6300 w/ Arctic Freezer Pro 7 @ 3.6ghz 1.4Vcore
Antec 900 Case
EVGA 750i FTW Mobo
4x1GB of G.skill DDR2-800
2 8800GT in SLI
22" Samsung Syncmaster
1 250GB WD and 1 Seagate 7200.10 in RAID 0
Corsair 520HX 3DMark06 Score: 13900