HTPC Linux build advice wanted

Getting ready to do my first build, been looking through message boards and reviews, still can't get past some threshold questions and would like some advice. Particulars: the machine is to function as an HTPC, to receive a TV feed from cable and output to an LCD television via HDMI, would like to use XBMC to access stored media (e.g. iTunes library), and want to use Linux as the OS. Would like to use it for a file server as well, to use on my home wireless network (the network has a desktop Windows XP PC, a Windows XP laptop, and Mac OS X laptop (soon to be joined by a second OS X laptop). And this Linux build. No gaming, just HTPC, Web browsing, and multimedia file serving.

My main quandary is deciding on a mobo. It seems to me that onboard graphics is good enough, and HDMI output would be nice (or DVI). Question: as between onboard graphics and onboard wifi/networking, which is more important (and which would make things easier for my build, in view of the planned Linux installation?). Size is not a concern, will probably use a rackmount case (to fit in my home theater setup). Would prefer an Intel CPU (just in case the Hackintosh spirit moves me in the future).

So: Any suggestions for mobos that would work for me? Any suggestions for choosing between onboard graphics/onboard networking/neither? How many additional cards (TV tuner, video, wifi) might I need given the suggested mobo?

All advice appreciated, thanks,
Dave