Okay so here is my understanding, correct me if Im wrong.
You can install Nvidia windows driver on MBP and you wont have problems with compatibility am I correct? Even though Apple uses EFI while PC use PCI-E?.
You are wrong on one part. The ability to run Nvidia windows drivers is not indicitive on whether a computer has EFI. EFI is basically a replacement to the BIOS (basic input output system). PCI-E (PCI-Express) is an expansion slot standard, kind of like PCI and AGP slots. The two aren't related.
Nvidia does not provide drivers for laptops. It is up to OEM manufactures (like Apple, Dell, HP, ect) to provide their own drivers to the users. Of course, these drivers are generally provided to these OEM companies from Nvidia, although maybe with some slight modifications. Places like laptopvideo2go provides laptop and desktop drivers and a modified file that allows these drivers to be installed on any laptop, regardless of manufacturer.
I went to Apple's site to download Boot Camp 2.1 and install it. It's basically installs/updates existing drivers. So, I would assume that if you wanted to install Vista 64-bit, all you would need to do is download these drivers from Apple, put them on a flash stick. Install Vista-64bit and then install the drivers.