If you're looking to upgrade, two GTS 450's in SLI will provide excellent performance without blowing too much money.
http://www.newegg.com/Product/Produc...-558-_-Product
(The one I got from BestBuy was stupidly overpriced. I'll never shop there again, even if it's secure, in my hands after the transaction.)
Installing Liquid Cooling yourself is incredibly difficult in my opinion, save a select few coolers. Since I haven't the faintest clue how to install one, we'll skip this subject.
I'd wait for the i5-2500k as well, but if you can't:
http://www.newegg.com/Product/Produc...82E16819115066
6 Core i7 3.2 GhZ. Though, you may need to upgrade your motherboard, as the i7 has been known to be incompatible with some. (Naturally, you'll see this wherever you go.)
Don't swear off AMD's either. AMD Phenom II's are great CPU's. (I'd have one if I could.)
http://www.newegg.com/Product/Produc...82E16819115079
The above is the fastest Intel CPU I think I could find un-overclocked at 3.46 Ghz on NewEgg. I'm sure there's faster out there, just having issues finding them right now, as it's stupidly late at night.
Scooba was right on with his post about your RAM though.