400d is a very sexy entry level slr digital camera, though it may sound vain avoid the silver finish as it scratches and the black looks far more pro (I have the lowly 300d, which i've had for nearly 2 years now). Invest in a couple of 1gb cards if you can too, look around in the internet for good deals, I have a super fast one I got for like $30. Man I spend way too much money on photography related products (processing, accessories etc).
The S3-13 is also a very commendable digital point and shoot camera and i'd probably get one of those if I could afford it as a party/everyday camera.
Canono's Ixus range is merely for sleek looks and families/people just wanting snapshots I personally believe, you're far better off with the smaller sized Powershot series (excl. S3-13). The Powershot series has the manual function which is quite interesting though nothing compares to a dSLR!! That or the G7 (hot, but like i'm an SLR/dSLR girl at heart :mad1
. I've used the IXUS a few times and I agree about the complicated "manual" settings.
If I could get any of the cameras, i'd get
dSLR - EOS 1Ds Mark II (Aim to get this before i'm 21)
Compact - Powershot G7
Super Compact - Top IXUS [there's not alot of variation between them is there?]