Virus infection of Microsoft XP system files.

Some of the computers we’re using were infected with a virus. The computer logs off after logging in with any user account.

I restored the registry of the system to be able to log in. This solves the problem of logging in. However, when I made a full system scan, the antivirus detected infection on some Windows XP system files, such as the explorer.exe. The antivirus suggests deletion or quarantine the files, but knowing that these ae system files I cancelled the operation.

My question is, is there a way to restore these files (possibly from the installation cab files) so as not to reinstall everything from scratch?