You should just go for one of the free anti virus programs.They never hurt anyone.
If u decide to go for one heres some freebies
www.grisoft.com
http://www.avast.com
OR if you can't be bothered get a free online scan at
http://housecall.trendmicro.com
OR if its Mydoom you're worried about download McAfee Stinger Avert
http://vil.nai.com/vil/stinger/
It also searches for about 37 other newish viruses and only takes 50 seconds to download on a pishy wee dial up like mine!!