[FormElement]

Really, it comes down to how much you can invest, and what you own. I assume that since you made no mention of lenses, then glass is another big investment you need to make.


5DII Base Investment: $7300
Body with 24-105: $3400
70-200 f/2.8 IS: $1800
16-35: $1600 (optional)
Add extra batteries, CF cards, etc etc: $500

7D Base Investment: $5700
Body Only (the kit lens will not do); $1700
10-22: $700 (optional)
17-55 IS USM: $1100
70-200 f/2.8 IS: $1800
Sundries: $500

The 5DII is a better camera for what you want to do. The 7D or 50D would both be excellent alternatives. The ISO performance of the 5DII is about two full stops better than any other canon body below the 1Ds MKIII. Two full stops is four times as fast! That's not chicken feed. The 7D is about 2/3 stop faster than your XSi and infinitely better in so many ways, but it is definitely not a low light blazer. Check my flickr stream. I shot a play rehearsal the other evening at ISO 1250 and even though I got the shots, the noise is there. Minding that I pulled shadows about two stops out of the black and skipped my normal NR processing so the background noise is hugely exaggerated in these shots!

One fair warning, when you go up the scale with your camera body, you wil also find that your computing and storage power go up too. Handling the file size and quantity that you will get with weddings and a new high res body will really load up your system fast.