I don't think the Xigmatek cooler will work with the i7 chip. I'm not aware of a LGA 1366 bracket being released for that cooler yet.
You also said you already have Windows. I hope your Windows is 64-bit or you'll only be able to use half your RAM if you go with the i7 build. I thought the 32-bit RAM limitation was common knowledge by now, but I mention it because I've seen quite a few people posting who installed a 32-bit OS on their new i7 build with 6GB of RAM and can't figure out why only about 3GB shows up.
What is the intended use of the computer? Obviously you'll be gaming on it, but will you also be doing video editing/encoding? If so, you'll probably want the i7 since it absolutely rocks at video encoding.
I would go for option 1, with the Thermalright 120 ulra extreme to go in your antec 900, and try to find budget for 295 as well as you will not need to upgrade at all, if you get that ati card your already doomed and limted, dont waste money on a lesser card, you wont have to upgrade after, if you waste on that cpu, your already outdated and will suck for any future multithreaded programs, , the difference in the cpu potential is lightyears apart so dont get core 2 HeLL NO, 8 virtual core forever....