Virus Help!

I encountered a backdoor Trojan horse just a few minutes ago. The name of the virus is backdoor.sdbot. It infected my syscfg32.exe in my C:\ drive. I use Windows XP and I have an anti-virus scanner called Norton Anti-Virus. I tried to repair the item,but it didn't work. I tried downloading extra virus definition lists and then tried to repair again,but that didn't work either. I would like to delete the item with the infection on it,but I am afraid it might be important. So I quarantined it and came straight here to get some help. Please help if you can! Thanks in advance! ^_^