Frankly, this is something I'd do a frankenputer of old or ebay/craigslist parts for. HTPC duties are not hard as long as you're only looking for media playback. Pretty much anything from the last 3-4 years would do it.
Heh: At this point I should admit "I've recycled my old Northwood 3.2ghz/ 6800 Ultra combo to do just that." (Some unquantified combination of CacheManXP, FireTune, and a DataRam RAMDisk for the
page file and temp directory was necessary to get playback of stream smoothed out.)
I'd asked 'cause I'd heard there was money to be saved on power consumption . . .
Thank you, Gentlemen!