40d or 500d?
Another possible good way to go is a 50D refurb direct from Canon.
Canon is currently offering these for $703. They are in like new cond. and come with everything in the box as new and a warranty.
Even better is if you have any old junky Canon P&S laying around it can be applied to your 50D refurb purchase using Canon's Recycle/Loyalty program.
This can get the 50D down to around or under $600 delivered.
Mine just arrived Wed and I am thrilled with it.