I can say this for the first time owning a mac. The mac pro has been the most trouble free, fastest, quietest computer I have ever owned period and I have owned many many systems. Go for it. Its upgradable anyways. To 32gb of ram now and the cpu's are replaceable. Damn fine machine.
I am lovin this intel move. Upgraded my mac mini and have the same potential in my mac pro. YES!
I'll second that!
My boss has a dual 2.66 and has had no problems.
I've had my mac pro (dual quad core - has no smell at all) for a week and a half now and I love it. Glad I didn't wait any longer for the rumored video or motherboard update. This machine is 8 times faster than my last PC when doing 3D rendering. The odds are you will be able to update the video card at some point anyway. The Mac Pro is fast, quiet, and extremely easy to add ram, drives, etc. Heck, the inside of the case is a work of art! I am running bootcamp with xp64 on it and with the exception of the eject key not working (which is annoying, but you can right click on the drive and click eject), I can't tell the difference between the Mac Pro and my office PC dual quad workstation - other than the Mac Pro is a bit faster and much more quiet. Oh, and the Mac Pro cost less! I have been using computers since the Amiga 1000. I have owned multiple PC's and Macs. So far, this system might be my favorite!
BTW, I added ram to it from Crucial (turns out to be the same brand that was in the Mac Pro I received - I peeled off the Crucial sticker on the heat sink and the sticked under it matched the Mac's ram sticker).
It's your call to buy or wait. The trouble is that when the next updates come out, then the next best thing rumor will have you thinking if you should wait just a little longer. The question is: do you need a faster computer, or do you want a faster computer? If you need one - go for it. If you just want one, you might want to wait. One thing about waiting and buying new technology when it first comes out - bugs. They are pretty much gone from the current OS X and hardware. They will most likely have problems with with a new OS and hardware, at least for a while.
Hope this helps...