I find XP to be like a car: if you do lots of maintenance (regular defrags, cleanouts and registry fixups), it lasts and lasts.
That's how I been trying to treat the thing, I hit up the ol' A/V scan (now if only AVG Free wasn't expiring permanently next year), SpyBot/Ad-Aware for spyware, and CCleaner for doing a lot of the hardwork for me regarding registry clean-up/temp files that are more like perma-temp files.
Now to actually get off my lazy butt, shut this PC off, and do some mem-stick swapping...
[EDIT] Seem to have no probs with the Event Viewer, so I guess my HD being a problem may be out of the question.