Sorry to hear about your theft crowd Makes me angry every time I hear about those thieves hurting good people.

I use Spybot/Hijackthis which is free from-

http://www.safer-networking.org/en/home/index.html

What Super recommends is the 100% way to be safe. Just a clean format... In the future try and have things backed up so a full format isn't as traumatic. Because we all know it sucks losing stuff.

Before you format though you should try and at least track down the source of your hack. Then format- secure yourself- buy an authenticator too.