CnoteChris, I believe I’m running the setup you want to implement. Well, I’ve got a tnt2 and a savage4, but the concept is the same.
Windows98 or 2000 has multi-monitor support built in. All you have to do is install another card and plug the monitor into it. Then you can set the respective resolutions etc. in the control panel just like you did before. You can also set the relative positions and sizes of the two monitors there.
Is that open video port you’ve got on your system on the motherboard or on another card? I got the impression that it was on the motherboard, which means that it is most likely automatically disabled when the board detects another video card. You can try plugging the other monitor into it and seeing if you get any results, but I doubt it.
There are a few things to be aware of. If you run OpenGL applications (recent 3d games, some screensavers, modeling software) you might have to temporarily disable the second monitor to run the program. This is no big deal, but if it’s why you were going to get the second monitor on there, think twice. The other thing to be aware of is that the bios must pick one of the cards to be the primary card, which is the one that all the boot stuff shows up on. It’s also the “main” screen once windows is up. In my case (I’m running an Abit BP6 motherboard), I could choose whether to have the AGP or the PCI as primary. It defaulted to PCI, which is absolutely stupid, but I changed it.
As to the other questions: Yes, the mouse automatically moves between screens, and you can easily drag windows between them and even leave them partially on both.
I’ve never used the Matrox card that’s been mentioned, but I got the impression you wanted to keep your voodoo, so that may not be the best choice for you.
Does this answer your questions? If not, I’ll try again.
Oh, and I just happen to have a lot of video cards that I’d like to get rid of. Care to buy one?