How helpful is that
Short answer to the OP:
- 5D has full frame sensor and is a bit slow. Good for landscapes and portraits, bad for sports and fast action photography.
- 7D has crop sensor, current features and is very fast. Good for fast action photography but rather limiting (due to crop sensor) for shooting landscapes as even ultra-wide lenses are not that wide.
Only buy 5D if you know you want it. It's very good in what it's good at, but you will be disappointed if you try to make it shine where it's not at its best.