Ok well if your going for HD like legit HD, not just recording in 480 and converting to 1080, your best bet is the Hauppauge HD PVR, which records the component video (YCrCb) connections and maybe composite, but im not sure about that one.
I currently have a dazzle which is cheap and quick, but I just put in an order for a Black Magic Intensity Pro
ok I just got my blackmagic and apparently there's a hdcp thingy in it now so you can't record the xbox through HDMI only component
This records in 1080i and is an internal capture card, while the hauppauge is external
some people say the intensity pro is better quality slightly, but they are both the same price, $200.00
also the Intensity pro can record in HDMI which was the winning factor that got me to buy it over the hauppauge
both cary a heavy price tag so I would check into youtube and watch some quality tests for the:
Dazzle DVC 100
Hauppauge HD PVR
Black magic Intensity Pro
and make sure you check specifications so everything will work, and happy machinima making
-Were on youtube to!- Arc Editing