No love for the PS2? I've been using a soft-modded PS2 (phat, with a 500GB HDD) for emulation and it's been working great. I've never used an xbox, so I don't know how well it compares to PS2 in terms of ease-of-use and emulating power. Although I suspect setting up Stepmania on xbox is likely much easier than hacking custom songs into the PS2 version of In The Groove...
I play games on: GBC, GBA, GBA SP, NDS, NGPC, Panasonic FZ-10 3DO, NES, Sega Nomad, Sega CDX w/Power Base Converter, PS1, PS2, PS3, Sega Saturn, PC, EGP1000, Dingoo A330, Gemei A330, LetCool N350JP, PAP-GAMETA, GCW-Zero SE, Kyocera Rise, and 2DS.
Currently playing: Legacy of the Wizard (NES), Cave Story (GCW-0), Zookeeper Battle (Android), Theatrhythm Final Fantasy (2DS).