i bought a 30d a few days ago and am beyond impressed with it. i toyed with the idea of getting the 5d, but i was not really ready to spend that kind of money. i got a decent deal on the 30d kit, and just ordered the canon 70-200 f/4. i have the 50mm 1.8, so i'm set, for now.
i was also a bit infatuated with the new rebel (i have a 300d) and came darn close to choosing that. but in the end, the wheel dial, the 5 fps along with other features, sold me on the 30d. SO, if you're trying to decide between the 30d and the 400d, my vote is for the 30d. it's way more sophisticated, imo.
it's true, i am in love. in fact, it looks like i've been kissing the viewfinder. it really gets smudged up!