Problem with Trojan Horse Virus

Recently my computer has been infected with a trojan horse virus.  I have no experiance in dealing with these situations and i would be grateful for any advice.  I have scanned my my computer with norton antivirus and it has quarentined two files one called adclass.exe and another hosts.vbs I have tried to repair these files but they are un-repairable.  I sent the files to SARC for them to be analysed and they recommended I deleted the files and replaced them.  But these files are windows files, does this mean I have to reinstall windows or locate these files from another computer and replace my own infected files?