Yeah, well Grimbles I guess you're right. But 2 years?? The longest I ever had a Windoze install last was a year, and by then it was on its knees...
I guess if Dave's was 6 months old, maybe a year, you could do stuff like registry cleanup, serious online / offline defrag, pagefile sort-out, junk file cleanout, disk error fix, major spyware hunt etc. But to be honest I can't see it getting back to square one if it's that age. I wipe mine every 6 months as a matter of course.
Maybe it depends on the use though. A lot of office machines would probably last well. But mine gets a ton of abuse. You know, the gambling sites, p1rate stuff, cr@x, DC hubs, p0rn sites, hack attempts, v1rus writing etc. Lucky to last a month sometimes