Livebriand gave you excellent pointers about old version Win-XP drivers in the new version Windows Vista/7.
If you are trying to get an old favorite program that ran on Win-XP to do the same in Windows7, and it's not cooperating, on the executable file right click to bring up the properties dialog box and try to run it in Win-XP mode. That 'might' get you an older program to run in the newer OS.
You only need the certificate for 64 bit drivers. Your older XP drivers "should" work under Win 7. That's not a 100% guarantee, but generally existing drivers do work on newer OS versions, Otherwise if you are not plug and play for a PCI board it will not work for Win7. It was extremely risky on XP, where depending on the system and the board a non-PNP driver may or may not work. Don't even friends trying this with Win7 or 64-bit, just throw out the driver and start over again.