You can't use both integrated (motherboard) and dedicated (video card) simultaneously. If you want dual screen, you will need a video card with two video ports. Tell us if you have AGP or PCI express, your current video card so we won't suggest a worse card and budget. You can't use two video cards unless you have an SLI or CrossFire ready system and I'm sure you don't have one because no video cars with this compatibility has one vga port.
Taking issue with this post.
1. You can use integrated and dedicated card. As long as you are using a dedicated pci card, not an agp card. Sounds like pouncer has a good agp card so this doesn't help but you can do it. (what I'm currently doing)
2. pouncer does not need a card with two video ports. You can use two video cards with no problem. If pounce is using the integrated graphics or has an agp card then all they have to do is get a PCI card. (read cheap 20$) and set it up in windows.
3. Crossfire and SLI are not for multiple screens they are for connecting two video cards to increase their performance. The two cards share info through the motherboard and depending on your settings each card renders every other frame or only the bottom or top half of the frame. The fact that SLI and Crossfire cards are on the high end and support multiple monitors is just a benefit that you can get with lower end cards if you look for it.
Best way I see without specific system specs is pick up cheap PCI card and install it. Then follow the instructions. Windows XP has support for some obscene number of cards . Easy peasy.
-grummle