Ad-aware
Ad-aware is a free multi spyware removal utility, that scans your memory, registry and hard drives for known spyware components and lets you remove them safely.
Ad-aware has worked well for me, and its free.
http://www.zeropaid.com/kazaalite/
Peer To Peer is still the best for Video downloads because it has "Swarming" connects. For Music mp3's use WinMX
http://www.Winmx.com