I installed a new 250GB drive in my MacBook as soon as I bought it in late 2007. All was well for over a year until first thing Saturday morning when I got the pretty damning "disk0s2: 0xe0030005 (UNDEFINED)" error which meant the thing was irrecoverably knackered. Thankfully I've been running Time Machine over airport at home for the last few months so was able to swap out the 250GB for the original 120GB, boot from my installation DVD and recover the system as of late Friday night simply by choosing the "Restore System from Backup". All worked flawlessly, good work, Apple!
It was a Samsung drive that failed, and it apparently had a 3 year warranty so is back at Streetwise right now getting a look see.