Got Ad-Aware, What Next...?

Hi - Iv just reformatted my computer with XP Pro with SP1 & SP2.

But what im trying to do is get some other good programs onto it that will help keep my beast running smooth.

Iv currently got Ad-Aware and Nortans System Works 2004 Pro. Just wondering if anyone could help by telling me some other programs which are good to help keep my pc fresh…??

Ben