Same boat.
Not really
needing a new Mac Pro, I would love a new one.
Got the 2008 Mac Pro, 8 Cores, 8 GB RAM and Radeon 4870.
This Mac is my "everything I want in a computer", i.e. gaming (OS X and Boot Camp) is also part of it.
Narrowing down why I
want a new Mac Pro: X-Plane 10.
I could get SSD inside and the Radeon 5870, but I feel I'm spending quite a sum of money updating an almost 4 year old Mac.
I'm definitely waiting for a new Mac Pro. Hoping same number of cores or more (that was a slight problem regarding the 6-Core Westmere 3.33GHz last year...), but also significant single-thread performance boost.
Especially X-Plane (9 and 10) eats GPU AND CPU. Getting a Radeon 5870 inside an '08 Mac Pro, and the performance gain playing X-Plane will be disappointing. Not in most games, but it will disappoint in X-Plane.
So, here's to a new Mac Pro, Radeon 7970 (2 GB VRAM), 8 Cores or more, 1600 MHz RAM, SSD, etc... all for a cute little price.

That'll give me about 10fps more on X-Plane 10.
