Help - Unable to run/install Windows Programs After Viruses Encountered

Unfortunately, I encountered three (3) viruses: Conference.Exe, Ave.Exe, & Ncuc.Exe.  After running Norton Anti-Virus 2010, I'm unable to install and/or run any Windows Apps (MS Office, Control Panel (Add or Remove Programs), etc...  I'm running Windows XP Pro.

 

Any assistance would be greatly appreciated.