I was looking at buying this receiver )Yamaha 5.1 Channel Receiver (HTR6040B))I noticed that it says it has no digital outputs
As for sources I would probally just use my xbox, and dvd player.
You don't need digital outputs from the receiver only digital in.
Something you might want to consider would be a receiver that has analog inputs and outputs for all 6.1 or 7.1 channels, this would allow you to use the receiver as a preamp and then add a seperate power amplifier later if you so desired, but this is now getting into a whole other post.
The HTR6040 will work very nicely if it suits your needs.