heh You'd surprised on how much processing power DivX movies take. My FV24 with P-III 933 cant play a DivX clip encoded at 720X512 284Kbps fast enough to sync with the sound. Not to drive the tread off topic, where did you mount your GPS receiver? Since you ordered one with magnet mount, I assume its on top of your vehicle.
My Eden5000 box has a slim, 8x DVD-ROM drive w/ PowerDVD software and so far it's real smooth (I've only tested playback using the Cowboy Bebop Session 1 disc).
By DivX, do you mean (.avi) files encoded with DivX? Any video player software should play them with the latest DivX codec installed...