Easiest way to improve performance would be to get another 1GB of memory.click here
Ditch PCGuard too and use one of the much better freebies available. click here
There are no published figures for the efficacy of PCGuard as far as I am aware and I've seen Avast clean up a system `protected` by PCGuard, which couldn't clear what it had picked up, and missed other stuff anyway.
AVG already has anti-spyware and safe-search features, adding antispyware product such as Superantispyware is not a bad idea too. Don't install more than one AV at a time. All available from the second link. You may find this interesting reading too; click here