It has begun to slow down incredibly. The hard-drive seems to work really hard for small tasks and opening and closing programs can take up to and including a full 5 minutes (programs like Windows Media Player, Winamp, and most web browsers).
I've done defrags, disk scans, virus scans, registry scans, spyware removals, all of which have not helped the situation at all.
512 MB RAM (though is registering as 480 MB right now)
55.6 GB Hard Drive (26 GB free space)
Windows XP Service Pack 2 (this may be significant, as it never ran on SP2 before)