I'd personally go with the P5K pro
. The P5KC is different in that it supports DDR2 and DDR3 memory, although DDR3 won't be worth buying for a long time. My philosophy is not to overcomplicate things if at all possible. Added to that, the pro is a newer release, meaning they have already updated the BIOS to allow compatibility with the newest 45nm intel chips (and updating the BIOS is something you should avoid if at all possible).
Either way, its a minor point.
The other thing is, see if you can't get everything at the same site, or between two: otherwise you'll be spending a lot on shipping.
Looks great otherwise, should be a really good build.