I had ask a very similar question when I was contemplating a switch from P&S to DSLR Cath, and got some very informative responses from members who took the time to reply.
You can find them here, and they may help in your decision about the 40D.
Canon EOS 40D, or 50D ?
As you will see, I opted for a complete outfit with an almost new XSi from 'Used Ottawa', at a price well within my budget, and am most happy with the XSi camera !
Goodluck with your decision. :thumbsup: