MSI P45 Neo-F, GeForce GTX 260 graphic card upgrade (Install resolved)

Question

Greetings,
We recently built up starting from an MSI P45-F motherboard and running an Intel Core 2 Duo Processor on XP (we did not choose XP-64 waiting on Windows 7).
We are attempting to upgrade the graphic card to the PCI express with a GeForce GTX 260 and are encountering a driver download error from Nvidia.
Problem/Issue: While driver software is downloading, mid-way the screen goes black/blank and a single underscore cursor appears (remains indefinitely).
We believed it could be a power supply issue as we are running an OCZ tech 600W stealth stream (we are certain there is sufficient amp), but clearly we must disable or uninstall the on-board graphic card (which may be causing a drain?).  We are looking under the Device Manager and unable to identify which is the actual on-board graphics in order to disable. 
I have attempted to contact MSI directly; however there is a communication problem on my part since I have no idea what I'm doing ($40 bucks to have the card professionally installed is looking like a bargain right now, but think of the fun I will have with the Crysis expansion set on ULTRA).
One side bar question, not important: I'm running 4 GHz RAM, but only 3.205 is appearing? what is the missing RAM being allocated to at idle (is that to the graphics?)?
Any assistance you could offer would be greatly appreciated.
Jay

Answer 1

Greetings,
Well - initially the lock up would occur when we started running the Nvidia driver download software.   After booting and performing a system restore (the normal OS load locked up, so we had no choice but to back date).  We then downloaded the driver from Nvidia on to a disk from another computer and started up the upgrading computer in safemode and inserted the disk, same error occurred - halfway through the install download the screen goes blank and stays with under score cursor 20+mins.
We called Nvida and they claimed there may be may be driver conflict, so we removed all the drivers (with a driver sweep software-we wiped out allllll of the drivers, no problem) and loaded all drivers fresh and brand new. 
Still same error occurred; We attempted to load the nvidia driver from the website -
Carefully confirming that
1.) we have sufficient amps (we calculated 46amps) to cover our build up. 
*EDIT: IT WAS ACTUALLY 18amps (ALWAYS DOUBLE CHECK YOUR CALCULATIONS)
2.) we also confirmed the motherboard has the correct slot and we correctly connected the correct (2) power cords. 
EDIT: THERE IS NO PRIORITY TO CONNECTION, SO JUST BE AWARE THERE ARE TWO PLUGS AND BOTH FIRMLY INSERTED.
We've called Nvidia and on the 5th time  , we were specifically told that it did not appear that the motherboard and graphic driver are compatible.[/flash] How could that be ??? did they give up???
EDIT: THEY WERE INCORRECT, THEY DID NOT DIAGNOSE THE PROBLEM CORRECTLY.
gfffffff*   We are just about giving up and preparing to package up the new card and taking the restock charge... 
EDIT: NEVER GIVE UP!!!