You might be able to save yourself some bucks and go the i5/p55 route. For your purposes I don't think the i7 will be of much benefit to you, but it is a reasonable choice if you want to go with the x58 platform. If you are sure you want to go i7, feel free to ignore me
I'd say that the biggest difference between i5 and i7 is that the i7 has hyperthreading. That means that in effect, it has 8 cores instead of 4, but not many things are that extremely multithreaded, unless you're planning on extreme multi-tasking, video editing, or hardcore photo shop things. Another benefit of the i7 is the x58 platform which may(?) have more upgrade availability, but I have no idea about the future of x58 and p55. Personally I would choose the i5, but if the i7 is within your budget and you're up to it, go for it.
If you did go i5, a great mobo is the ASUS P7P55D-E PRO. It has two PCI-E ports (x8/x8) and has all of the new ports as well (SATA 6, USB 3)