Why not
If you have all the necessary hardware, which I assume you do, it wont take more than 5 minutes to try and you've got nothing to lose. If the monitor doesn't show any BIOS info on boot up of the PC, chances are it isn't going to work. But I don't see why not. It's just a video card and LCD monitor. Make sure you know exactly what model GeForce 4MX you have (400, 420, 440 etc) so you can download the proper drivers.
If you have another monitor, maybe you can first hook that up to the GeForce once its in the PC. Download the newest drivers from nvidias website for your card, then plug in the LCD. Thats the only *alternative* to just plugging them in and turning it on.