I remembered. It's the PC Buddy. I don't think that they're still in business, but you might be able to find one somewhere. In fact, I might be able to find that old one we had. Maybe, as I think I know who stole it after we couldn't get it to work at the office (not me).

Edit: Seems like the PC Buddy was actually just a bundled set of the BeTwin software and an ordinary video card. BeTwin is still in existence, but they only seem to have a Win2k app now.