There's most likely two areas to tackle.

1. Resources.

The Memory and Optimizing Windows articles at http://www.aumha.org/articles.htm are useful.

2. PARASITES. These can no longer be tolerated. Let me state that your antivirus does not detect/remove all PARASITES! I consider SPYWARE, ADWARE, VIRUS and TROJANS to be lumped into a category I call parasites. Symantec has yet to WAKE UP! to the spyware/adware parasite issue.

Parasite removal programs.

http://reviews.cnet.com/5208-6132-0.html?forumID=32&threadID=1313&start=0 notes the five scanning tools and removal tools that are fairly safe. If one does encounter an issue, its always been damage done by the MALWARE. The most common issue being Layered Service Provider replacement which you can use LSPFIX (Hint: use http://www.google.com to find).

The thread has follow on discussions about new links if you don't want to use Google to find an item.

Bob

PS. All the tools are free.