I was guessing that the NVIDIA remote's software is organized in a similar way as the ATI. Doing a quick search on the net suggests that your X10 driver is found in Device Manager under Universal Serial Bus controllers as NVIDIA Wireless Remote Receiver. You always need a driver here, try with the one you have, try with ATI's, or software for any other clone of this remote control (there are heaps!) like Niveus http://www.niveusmedia.com/gallery/rc_full.htm.
The driver takes care of making the remote button presses available in your system. Then you need an application that listens to these button presses, convert them into the desired keyboard keystrokes, and send them on to the desired application window (MCE in my case). This is where I ditched ATI's software (ATIRW.exe) and instead used RW Key Master / Factory to get more flexibility in key assignments. My search suggests that the corresponding NVIDIA application in your case is Nvarem.exe which you will find as a running process and autorun. You should make sure this doesn't run (you don't have to uninstall) so remove the autorun and terminate the process, or reboot.
So, my first recommendation is to try RW Key Master / Factory with your existing driver. If not ok, try with other manufacturers' drivers together with RWM/F and remember to disable their corresponding "applications" that are usually installed at the same time. If you still have no luck try other X10 applications instead of RWM/F, like x10rc (there are more if you look around). You need to find the combination that works with your hardware.
Sorry, not owning this hardware I cannot help you more than this so you're on your own now. Remember that Google is your friend and also do not forget NVIDIA's own forums at http://forums.nvidia.com 