Forget about your GPU(s). To restate what has been already said above, you need enough RAM and a fast hard disk (preferably SSD) so that you can compile/build and switch between IDE and game without having to wait for swap, and 4+ CPU cores to have your game, your IDE and your build tools smoothly running in parallel. For GPU, a mid-spec GPU is enough, since it already covers most high-end features (except that it is a little slower) and keeps you attentive to your target audience's hardware. If you're going to work on media such as 3D graphics, movies and so on, you'd profit from beefy GPU; although since you'll be programming, that's a moot point.

I'm bouncing you to the lounge - this doesn't really fall under the heading of "Game Programming".

Forget any ideas of writing an MMO

I add my agreement to the recommendations for an SSD - imo it's the best thing you can do to speed up compile times (or the computer in general).

I find NVIDIA's Optimus technology useful - with NVIDIA and an Intel CPU, you can switch between the graphics card and Intel GPU, even on a per-application level. Whilst intended for improving battery life on laptops, it's useful for developing, meaning you can test on two different makes of GPUs (and ones at rather different levels of performance) without having to reboot/swap cards/keep an old machine around.

I find lots of RAM useful for running VMs to test things work under a clean build, or try different Linux distributions. Even there, my max usage is about 7GB (out of 16GB).

Some compilers support multiple cores.

At its most basic, you don't need much at all. I also do programming on my Atom-based netbooks. Full release builds are a bit slow, but otherwise it's fine.

I have this current rig:

- i5 2500k 3.7GHz (quad core)

- HD6950 2GB GPU

- 12GB 1333MHz RAM

- 120GB SSD

- 500GB x 2 + 2TB hard drives

And frankly, it is 99% overkill when it comes to programming. I barely use 5% of its potential outside of games and scientific applications. Really, a $50 graphics card, a core duo CPU and a few gigs of RAM (I would vote for 6 or maybe 8, memory is dirt cheap at the moment) and you'll all set. Get an SSD too, it helps a lot. Add stuff as your budget dictates, but 32GB of RAM? Dual top-of-the-line graphics cards? Come on. Maybe a handful of individual people on the planet have this kind of hardware.

In fact, if you are going to be making games, I'd think hardcore gamer hardware (like what you suggest) is in fact detrimental as you are more likely to immensely overestimate your target audience's computational resources. If you go down this route, make sure you have some crappy hardware to test your game's performance on. You know, as a "real world" benchmark

I have this current rig:
- i5 2500k 3.7GHz (quad core)
- HD6950 2GB GPU
- 12GB 1333MHz RAM
- 120GB SSD
- 500GB x 2 + 2TB hard drives

And frankly, it is 99% overkill when it comes to programming. I barely use 5% of its potential outside of games and scientific applications. Really, a $50 graphics card, a core duo CPU and a few gigs of RAM (I would vote for 6 or maybe 8, memory is dirt cheap at the moment) and you'll all set. Get an SSD too, it helps a lot. Add stuff as your budget dictates, but 32GB of RAM? Dual top-of-the-line graphics cards? Come on. Maybe a handful of individual people on the planet have this kind of hardware.

In fact, if you are going to be making games, I'd think hardcore gamer hardware (like what you suggest) is in fact detrimental as you are more likely to immensely overestimate your target audience's computational resources. If you go down this route, make sure you have some crappy hardware to test your game's performance on. You know, as a "real world" benchmark

mine:
Athlon II X4 2.8GHz;
GeForce GTX 460;
16GB DDR3;
4TB HDD (2x1TB + 2TB), + 2TB external.

However, it's also handy to have a crappy old PC around the place (even if it's not your main one) for testing your game. For compatability testing, it's also good to have PCs with Intel, nVidia and ATI graphics cards, etc, etc...

This is one of many reasons why I love virtual machines. I specced out a fairly beefy laptop when I had to replace my last system (laptop because I was in school at the time and needed mobility) because I wanted the space and resources to be able to run virtual systems in tandem with my host.

While not a solution for changing the graphics hardware variable, I now have a few ready-to-go tiers of processing power to test installers and game demos on when I want to see how my software measures up. It's also a cheap networking test :)

To that end: if you're doing graphics work (especially high-res or high-poly), and to be able to accommodate parallel virtual systems if you like that idea, I'd still push for a high-memory, powerful-graphics, large-storage, competently powerful-processing system. The fact that those same properties do well in a gaming system doesn't hurt my feelings, but YMMV with productivity if your dedicated workstation also happens to be your main gaming rig :)