I am afraid there will be a problem.
You want to use a CP that is 3 years old with a Software that is about 6 to 7 years old.
The driver for the CP 5512 is part of the installation of STEP 7... I think beginning with V 5.2 or V 5.3, SIMATIC NET or WinCC flexible... but I guess only starting with Windows 2000. So if you have this V 5.1.3 of STEP 7 you either upgrade your STEP 7 Software to higher version... maybe on XP or you try to install SIMATIC NET, on your risk, and it might work... but you would need a SIMATIC NET version that supports Windows 2000 and the CP 5512. This is a tough one.
I would upgrade STEP 7.