I've bouncing around between these two camera bodies....the 40D or Rebel XSI. I looked at all of the specs on each one, and they look pretty much the same.

What's the better body?

Thanks!

Both are excellent cameras. The 40D is one of the mid-range models
and the XSi is from the cheaper Rebel (xxxD in Europe) range.

What led you to these two cameras? It is 3-4 years since they were released.

In terms of image quality, there is little to choose between them.
The 40D is bigger and heavier. This can be good or bad depending
on your individual requirements.

The 40D is faster. That wouldn't matter much to me, but it could be
important for some sports or wildlife shooting.

The 40D has an extra LCD display on top of the camera.
This is convenient, but not a big deal either way.

The XSi has slightly more resolution. 12 vs 10MP.
Again, this is not something I would worry about.

The biggest difference between the two is the viewfinder. I recently
had a look through the viewfinder of my brothers 40D and I was quite
surprised by how good it is compared to the pentamirror viewfinder in
the Rebel/xxxD cameras.

If the 40D is in good condition with a low shutter count, it is probably
the better of the two. If it has a high shutter count, it is probably best
avoided.

That's for the info, I really appreciate it. The reason I'm looking at those two cameras is because that's what has been recommended to be by friends as good "beginners" DSLR's. I can get a nice used D40 or SXI body for under $250-$400....and that's right in my price range. I'm wanting to get into a good DSLR, just not wanting to spend $1000+ on a body....and I thought that either of these two cameras (D40 or SXI) would be a great starting point for me.

Is there anything else I should look at?