http://www.bestbuy.com/site/olspage.jsp?skuId=9180628&type=product&id=1218046802510
The one that a linked to above is a power house for it's size,but it's not as pretty as the Mac Mini,and runs around 999.99.and like whats already been said,you're stuck with Vista 64 bit.
WOW that thing has some amazing things in it like quad Core,esata,water cooled,but it DOES NOT have a WIRELESS CARD!!!What's up with that.
Woah, those are some pretty impressive specs for such a small size. Its still far bigger than the Mac Mini though, its about 3-4 times as big in terms of internal volume. Just look at the optical drive slot and you'll see what I mean. Still, very impressive specs for the money. 2.66GHz Quad Core, 4GB RAM, what looks like two 250gb 7200rpm drives is a raid setup, dual 9800 graphics in SLI. Like you said though, lack of wif is a little lame.