The MSI MEGA PC train is gathering steam. We liked the MEGA PC when we reviewed the first model, but we wished for a less dated chipset. Looks like we'll get our wish in late September, when the MEGA 180 debuts. Based on the nForce2 with the IGP northbridge, this box will have one each of AGP and PCI slots. What's more, with a new black finish, it looks even better than its predecessor.Be sure to check out the picture.
Dave -- I think we should base your multimedia PC on this. Of course, Tech Report has the scoop on an Abit SFF that looks really cool as well, this one based on a P4 motherboard.
With both of these systems, I still kind of despair that you could run Linux on them and still have everything work. And since you can't buy Windows XP Media Center separately, this means cobbling together a system on top of Windows XP, with (potentially) lots of third-party apps to get all the functionality you want.