Rebuilding SFC in Vista...

Some months ago I ran sfc because I supposedly had some corruption in my system files. It didn't really work and in the process I went to purge the sfc cache in order to rebuild it. It purged the cache but also failed to rebuild it. I want to get the system files fixed before 04/13/2010 for obvious reasons and I really don't want to do a system restore from the recovery partition if I don't have to. Gateway, who made my computer, was completely worthless and tried refering me to their pay for number.

It's a Gateway GM5478 PC running Windows Vista Home Premium 32 bit. I had it for about two years and I was wondering how I would go about forcing SFC to ask for the DVD so I can either restore the files or the cache.