I would pick an XXD range over an XXXD any day, purely because of the build quality, with a magnesium body compared to a plastic one of the XXXD range they just feel much more solid and the switch gear is more substantial
indeed, having had my 50d for a while now, i picked up my 350d to give to my dad for his holiday the other day. I couldn't believe how light and less sturdy it felt, great starter cameras but the XXd really does feel a lot different and i personally wouldn't go back now.
50d is a wicked camera, think i'm the only one on here with one but i would fully recommend it, not touched the 500d but even though it has the same stats (except speed i think) it will feel cheaper, when they are similar in cost.
The video thing on slr's is a gimmic, no-one is using it massively as predicted, its maybe a 'nice' feature to have to say that you have it but, leave the video for the video cameras or the pro's who can spend hours setting up shots with different lenses and then hours editing it afterwards, not my idea of fun.