New Hardware or Win 7?

Hey everyone. I am currently running an AMD X2 4400+ with 4GB RAM, and two eVGA 8800 GTS running in SLI, and a 75GB Raptor HD for the OS and games, with a 500GB drive currently used for storage.

In addition to gaming, I also do system/server administration and consulting from this computer. As part of that I'm currently running the Windows 7 RC1 build released over the summer.

Now, within the next week I will be getting a check that will allow me to do an upgrade, but I'm in a bit of a quandry. I only have enough to either upgrade the hardware (looking at an i7 860),

OR

Get Windows 7 (which I will eventually have to get anyway).

This is an issue because I won't have the resources to do anymore upgrades probably until around Tax time next year.

The catch is, if I buy the hardware, I'm strongly leaning towards going back to a Vista install so I don't have to worry about the shutoffs, and to a lesser degree, the minor bugs I'm having using the Windows 7 RC.

So the final question boils down to, hardware or software? Software will be cheaper in the short term, but I'm already having noticeable performance issues with my current hardware. Can I get some feedback? Thanks!