300d user looking for a new body

Well, like i said months back I was waiting to see what the 5d MKII would bring.

That said, with my budget i am looking at the 40d, 50d and 5d MKI. I don't know what's worth it. I've been shooting with my rebel for awhile since the XT was released and my teammate bought one and sold his rebel to me.

I am still in college still and have several photog classes now and am now a regular shooter for our school paper this semester. I just ordered a 580ex II of a forum member which should be here in another day or so.

I just cannot deal with 2 aspects of the 300d any longer...

buffer, reading and writing: a real issue for me. My largest complaint. Not to mention the pesky issue of it writing corrupted files and restarting whenever the CF card is removed several times in a row.
AF: Its rough with my 35L and 135L getting accurate focuses in good light let alone low light. MF is close to impossible imho but maybe I am still new to this?

Thus, i feel its time to upgrade the body.

I've also been asked to take some pictures at an upcoming wedding(s) (not as the pro photog but to try and capture moments the paid guy may miss or not think of).

I also am working with a band for some show/promo work and find shooting concerts (on real stages with full light setups) very difficult with the AF on the 300d not to mention anything over iso400 is really just aweful in terms of noise.

Any input would be useful. I think the 40d would probably fit the bill fine but I really like to use my 35L and 135L at their actual distances on a full frame and he 5d would fit that too but the 50d with its micro AF adjustment seems very useful to me as well.

Lens i own: 18-55mm kit, 35L, 135L, 70-200L f/4 IS. I would like to purchase the Canon 15mm fish eye and an 85mm lens (my budget would be the 1.8 but the L is a dream) in that order as my next glass but that won't be for a bit.

Any of those will be a real step up. The viewfinders are much brighter (and significantly larger on the 5d), making MF much easier if you need it. I think in terms of image quality there's very little to choose between them (with the 40D perhaps trailing the pack slightly). Personally, I'm going for the 50D because its AF system suits my needs better than the more centre-oriented 5d and 5dII (and, er, it's half the price of the 5dII :/). If you go for a 40 or 50D, get the EFS 10-22 rather than the fisheye, you'll find it far more useful.