The 5D is great for portrait or landscape. it uses a DIGIC II processor so the same as in the XTi I havew and haha it's funny you're talking about getting a 5Dc I just bought one last night haha. It's burst speed is nothing to write home about 3fps or so and it's AF does leave something to be desired. But if you're shooting high speed that's what your 7D is for. I also am selling my XTi body and already bought a 1D Mark IIN (8.2MP with 8.5fps burst speed) for fast action. It's got a 45 point AF system with a bunch of cross types. If you're looking for something that will do what you need and can take heavy use though I'd go for the 1D series body. Built like a
tank. The 5D is the same build quality as the other xD series but nothing will touch a 1D.
Personally between the 2 I'd go for a 1Ds just because well it's a 1Ds and it has better AF and such and with a 1Ds classic I can bet if you bought it your 7D would be collecting dust soon enough. A couple budies of mine also bought 1D MK II's recently and their 60D and 7D are sitting on the shelf while they shoot with a 7+ year old design that gives better IQ and can run the burst speed of most other cameras (1DX aside) into the ground.