Start with some light tweaking here:
http://netsquirrel.com/msconfig/
I also recommend using 'Spybot Search & Destroy' as a complement to Ad-Aware. (Remember to update the definitions before you scan) Grab Spybot here:
http://www.safer-networking.org/en/index.html
A reg-cleaning wouldn't hurt, grab
Jouni Vuoros great cleaner here:
http://www.worldstart.com/weekly-dow...cleaner4.3.htm
After all that run a full system online scan for viruses:
http://housecall.trendmicro.com/hous...start_corp.asp
Theres alot more to this but hey it's a start..