What is the cheapest combination of two low-profile video cards to run Vista Aero Glass on 3 to 4 monitors?

This is for a work machine (Dimension C521) I’m at my wit’s end going back and forth from site to site trying to put together a combination of cards. I have only 3 slots on my workstation: PCI X16, PCI X1, and regular PCI– in that order. All slots are LOW PROFILE which limits the cards that will fit. With Vista, you can’t mix-and-match like XP or 2000. The two cards MUST share the same drivers (so no ATI + NVidia combinations) The PCI slot at literally at the bottom of the case, so no cards with huge fans or heatsinks will fit there. Similarly, the PCI X16 and PCI X1 slots are next to each other, so a PCI X16 + X1 combination would require the PCI X16 card not have an overly large heatsink or fan. Both cards must support the Vista Aero Glass interface and more than likely will have 1 DVI and 1 VGA (which is fine). The primary card (X16) must have at least 128MB RAM, 256MB preferably. The secondary must have at least 128MB RAM. Total budget? $150, but the lower the better.