I also have a Tyan 760MPX board. The first, very important, thing to do is to go to Tyan's site and get the latest bios version. Server boards in general and the 760MPX in particular often have a lot of conflicts because of the way their expansion slots are setup. Having the latest bios can get rid of some strange or just plain annoying conflicts, I should know.
It might also be a good idea to flash your 1000MT adapter on another STABLE system. The 1000MT actually has some post issues with certain hardware and the Tyan 760MPX is one of them. You can trace that down on Intel's site but it is a bit hard to find (if you need a link let me know). Make absolutely sure you grab the right flash file for your model of network card, assuming your card doesn't miraculously have the latest firmware.
If it helps any, my 760MPX is working fine with a 3WARE 8500-12 in one 64-bit slot, an Intel 1000MT 64-bit adapter in the other 64-bit slot, a Highpoint RocketRaid 1540, and Intel 1000MT 32-bit adapter. This is after updating bios and firmware on the cards and mobo.