4 Channel Video pci card ?

It seems like we had an Avermedia card doing just that at my old job. Not sure if you're looking for stretched display across two monitors or switching to the second monitor and displaying there alone?

Here's a link to one of their products which might do the job for you:

It's called "AVerDiGi NV7000", a 4-channel PCI card that will record audio and video onto your hard drive. According to the company's website, "Real time display and recording, a pure MPEG4 hardware-compression solution! Our top of the line Windows-based digital surveillance recording (DVR) solution that provides remote recording & monitoring, digital video archiving, password protection, and much more. Audio and video recording in synchronization. Also stackable up to 4 video capture cards. Now you can also take advantage of a meshed IP / CCTV Camera infrastructure for your daily surveillance needs."

We carry AverMedia in our online store. I haven't personally tried it so I can't vouch for the performance. The specs look ok for what you want to accomplish though and their prices are reasonable. If you're in the trade, you can order from any of the major distributors. I mostly sell to DIYers.