(Updated info) I have a trojan on my computer?

i know i asked this before but ive updated it now =)

Basicly my virus protection is called Avira Antivirus protection or something like that and it has told me that i have a trojan or virus called BDS/Msnmaker.AG.3 it wont delete it or anything and i have also downloaded spyware doctor which has told me that i have 3 threats and 7 infections on my computer.

Im only 14 so i cant go and buy a virus protection program and i was wondering whether restoring my computer to factory settings would get rid of all the viruses?

But it would also get rid of microsoft office which i need, i wouldnt be able to get it back either without a disk but we dont have it anymore so i dont know what to do! My main problem is getting rid of all the viruses.

Any help would be really apreciated thanks!

(Updated info) I have a trojan on my computer?product key

go to http://housecall.trendmicro.com They will let you run a complete scan for free and they will help erradicate out all of your computor's virus's worms, trojans and spyware. I've been going there once a week for years and I've brought many of my friends computors' back to life.

(Updated info) I have a trojan on my computer?triumph

http://www.avast.com/
Do what backpackwayne says... I have AVG on my computer and it cleans everything off it.
you must know that Anti-Virus program don't work very well in the Normal mode...you must use them in the Safe mode.