Hi there,
Welcome to the world of DSLR!!!
Depending on your budget. You should try both DSLR, get the feel. I know the 500D body is light and small. I will go for the 50D instead depending on your budget.
If you are thinking of upgrading your body later than you should go for 2nd hand. Just make sure that the body and lens you are buying are in good conditions. No cracks & dust inside the lens and the body sensors are cleans. Whether got warranty is up to you, if you mind. Make sure it's a local set not a export set.
You can go John3:16, SLR Revolution, CP, AP. Feel the camera and also enquiry the prices for both 500D & 50D. Decide later. Buying a DSLR is a heavy investment. Think it carefully...
Hope this help.