WD Raptor has one of the longest rated life expectancies in the world at 1.5 million hours. Also has a 5 year warranty. As a boot and OS/application drive they cannot be beat for speed. It's probably the single most effective speed upgrade you can make for your PC.
I have 4 running here, one of the oldest ones died due to a bad platter (lost sectors), the others have been running 24/7, one for about 3 years.