Any Dell XPS system users here? Using two video cards?

Hi all,Any Dell XPS systems users here, particularly 710 series.I have a Dell XPS-710 which came with a Nvidia 8260 256mb Direct X 10 capable video cardNow the MB of this system has 2 x PCI express cards slots ( oh it also has one PCI 12 express slot, anyone heard of what that is for?.looks like a shorter blue slot version of the PCI 16 express slots.I've been told but others ( mainly Dell support, and some dell XPS users) that I need to use exactly the same video cards for Vista to use both to run Duel monitors.So this configuration will not work.1 Nvidia 8260 card and 1 Nvidia 8800 GTX 746mb card.I was wondering if any Dell XPS systems users here can say if this is correct or not?I know one could connect the two monitors to the two DVI slots on the 8800 card, but why waist the 8260 card?Footnote to this late last year MS released a hot fix for this very issue, but I've not tried it out as it was unclear if it was for different video cards or not.Thanks in advancePhil M