Aye, it's PCI-E. My other box has an AGP port and it got cranky about the 7900 so I had to get a new card for that one too hehe. Ended up with a very nice bargain price on a 6800 card with 512mb. Roughly translated from my currency it was in the neighbourhood of 150 bucks or so.
The 7900 is another story though hehe. But I've always held the firm belief that it's more fun to pay a lot every few years rather than dishing out smaller amounts more often. Also, I got inspired by the impeding release of Oblivion so I felt an upgrade from my old X800XT was in order.