dromer

I use Free Download Manager, it's small uses few resources and does anything I expect from a download mananger.

Diskeeper, primary because it replaces the default defragmenter which seems 'cleaner' somehow.

µTorrent, it has most of the options of azereus and uses only a fraction of the resources. For stuff I can't find on Bittorrent I use eMule.

AVG though I'm thinking of switching to NOD32.

Ad-Aware and Hijackthis. Coupled with Firefox I've never had any problems.

Sygate, because it's the least bloated.