In Safemode, check the registry keys in HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run for questionable paths and delete them. Run MSCONFIG.exe and in the Startup tab uncheck any more questionable paths.
Reboot the machine to a boot disk and run another updated virus scan.
If your registry and msconfig are clean and the virus files are removed before rebooting, you shouldn’t have to boot from the boot disk. But it will make sure everything is clean.