Is System Compatible?

As far as I know, they will work. As sick as that GTX260 deal is, I'd look into getting an ATI card for crossfire purposes. You could crossfire these, or get this. The 4770s would perform better, the 4870 slightly worse. Of course, getting the 4770s would leave your board full anyways. eh.

Long story short, I've just giving you other options. The 4770s would perform amazingly, and the 4870 would leave you upgrade room. The GTX260 is a beast of a card as well, though and that's a good deal. If you have the little extra money, I'd get the 4770s, if you have an interest in Clear Sky, get the 4870. Otherwise, up to you.

Just do it yourself. Watch a youtube tutorial, read an article or two, get help here as needed. It's not hard.

I'm not sure you got what smithereen was saying.

That's a crossfire board, so you cannot use a second GTX 260 on it.
If you want to leave the option of crossfire open, get a 4870 1GB card for it now.

For the case, this one has all the design features:
http://www.newegg.com/Product/Prod [...] 60&Tpk=HAF
It may not suit your aesthetic sense, I realize, but in every other way it's the better case.

There are a few other cases I could recommend as well. The Thermaltake is good, if you must have it.

The 620HX is a nice one, but a bit light for future crossfire.... How about this?

Antec 1200 case and 850W PSU
http://www.newegg.com/Product/Comb [...] mbo.193730
That gives you a truly top of the line case and a very nice PSU... maybe a bit more power than you need, but that's just longevity.