GDDR3 is already out. GDDR4 I believe is out as well, only on one card though; the ATi Radeon X1800XT. Because in ATi's website they make mention of GDDR4 compatible, yet I haven't seen it for sale.
What I think you're referring to is DDR3, which hasn't come out yet. DDR RAM is your system memory, GDDR RAM is Graphics Double Data Rate RAM, you can't use GDDR style in your computer, you have to use DDR or DDR2 for right now.
But Dual-Cores are now the real big thing. The Athelon 64 X2 series processors are leading the way, with intel catching up at an alarming rate. AMD is winning right now when it comes to the Dual-Core race, but we soon expect to see intel launch a new chip boasting a better Dual-Core, or rather a true
dual-core, because the Pentium D is not infact a Dual-Core, but rather a Double-Core. It uses two cores on a single processing package.
Anywho, if you want a next generation computer, get a dual core CPU, DDR2 RAM, a graphics card that uses PCI-Express and has 512MB GDDR3 RAM, along with a Socket T (LGA775), or wait for the new AM2 socket to come out. Also, CPUs will start to all be using the 65nm die, currently intel only uses the 65nm die on its processors, but AMD will soon be following.