You don't mention the virus name it was given and if Frank is correct (as usual) then Delf is a trojan and repair isn't an option.
You have done the right thing, 'first do no harm' don't delete, send virus to the chest and investigate. There is no rush to delete anything from the chest, a protected area where it can do no harm. Anything that you send to the chest you should leave there for a week or two. If after that time you have suffered no adverse effects from moving these to the chest, scan them again (inside the chest) and if they are still detected as viruses, delete them.
Since this infection is in the system folders, deletion, etc. system restore could end up saving a copy in the c:\system volume information\ folder so you may see another detection in this location later.
Also to place files in the system folders you need permission. Whilst browsing or collecting email, etc. if you get infected then the malware by default inherits the same permissions that you have for your user account. So if the user account has administrator rights, the malware has administrator rights and can reap havoc. With limited rights the malware can't put files in the system folders, create registry entries, etc. This greatly reduces the potential harm that can be done by an undetected or first day virus, etc.
Check out the link to DropMyRights (in my signature below) - Browsing the Web and Reading E-mail Safely as an Administrator. This obviously applies to those NT based OSes that have administrator settings, winNT, win2k, winXP.
