Your commit charge is a bit high, for only having 640 megs of ram. You have a lot of processes going to. Mine usually overs at 32-35.

Things I'd remove:
adsub.exe
spysweeper
wwsecure
mclogserv
Hwapi.exe
(use firefox, get some secure extensions like adblocker, noscript etc..) and that will get rid of the majority of the spyware, adware, soft that has to be running on your machine)

Then install Lavasoft, and spybot search and destroy and you should run these programs every week or every other week to remove any malicious spyware or adware.

Then I'd get rid of
ipodservice (you can remove this until you need to sync your ipod, unless it was installed with Itunes and then you can just manually run itunes)
weather (firefox has a wonderful weather extension)
siteadv
stylexp (unless it is crucial to have themes)
dkservice (you can run the diskeeper manually)
MSGTAG (unless you absolutely must be notified the minute you receive email messages... otherwise check your email at your convenience)

And I would ditch all that McAfee stuff. Get the free version of Kaspersky and you should be set.

It sounds like your system is suffering from too much prevention. But in a way that is good. All that stuff you have on your machine helps prevent the nasties from entering the system. However it can affect your system performance.