HP734n (again) and Matrox cards

Thanks for the previous help you have given me. I've got the HP up and running now with a Matrox G450 dual head AGP card. My next question...

Can a Matrox G450 dual head PCI card be used in conjunction with the AGP one that is already installed? Yea, I know, 4 monitors is alot, but I play with music on the computer. Cubase and Fruityloops already push me for space on 2 monitors. I sometimes have 4 or 5 audio programs running at once, and it would be nice to spread them all out instead of constantly bringing an ap to the foreground. I could get bigger monitors, but I already have a bunch of 15-17 inchers, and it seems that another card would be way cheaper than new, larger monitors. Thanks.