If the card is pci-e, then you should be ok. But check the power supply requirements. Some high end cards, such as the 9800gtx and 4870, require about 24 amps on the 12v rails to work. Plan on spending at least $80-125 on a decent power supply to run one of those cards. Also, some long cards don't fit in micro-atx cases, but most will work ok. They also take up more than one slot frequently, meaning you can't use the pci slot next to one.