Dude im sorry but a 3ghz P4 and 1gig of ram is oldddd!!!!!!!!!!!!!!!! I cud prolly build a PC of that spec for about £60.

AVG is aload of bollocks, hogs system ram and processor cycle's!!

Fresh install install is my sugestion WITHOUT the bullshit anti-spyware and anti-virus crap. Ive never used any of them and ive NEVER had a problem.