Not a bad choice of kit tbh, the corsair power supply is fantastic (i have one), but you might find yourself needing a 750W one instead if you plan on overclocking by the end of things, and hey.. with an i7 920 as people have said before, it would be a crime not to!
Unfortunately with regards to your RAM, the price has jumped in the last few months.. I paid roughly £80 for 6 gigs of triple channel 1600mhz xms3, which is really cheap considering todays prices!
If you're into saving a bit of money:
The H50 comes with a fan of its own, and you should also have a case fan where you need one bundled with the antec 1200 so you may not need the extra one, the antec 900 is a nice case but you may struggle to fit your 5870 in there.
If you're not going for serious overclocking, the SE is nice to save some pennies, I'm not sure on the exact difference between the SE and the normal, but I'm pretty sure you don't lose much between them.
your build is remarkably similar to mine, though i went for a couple of cheaper parts so i could afford my huge monitor
