You'll also need NVinject.kext to get your Nvidia card working (there are other ways to do it, but this is the easiest AFAIK). Some Nvidia users need to edit the Info.plist found inside the NVinject.kext (as well as GeForce.kext and NVDAResman.kext) to add a DeviceID for their card, but your card is relatively old enough that the DeviceID should already be there. You can get NVinject here:

http://nvinject.free.fr/downloads.php

Also, you'll need this patcher:
http://tinyurl.com/39csng

Follow these instructions:

Unzip the patcher in the root of your drive
Install the Graphics Update - download it from here:

http://www.apple.com/downloads/macosx/apple/application_updates/leopardgraphicsupdate10.html

before you restart, put the NVinject.kext in your /System/Library/Extensions/ folder and repair permissions (very important!)
Restart now and boot up with -s option (single user mode)
mount your volume as writeable by typing the following at the prompt:
This time, boot up with -f (just reinitiates the kernels)

Should work. If not, do a search in google or insanelymac to find solutions for your specific card with this update (may need to edit Info.plist as I mentioned above). Good luck!