Do you need to run the 64 bit Kernel? I can't run it on my 2009 MacBook either (unless I hack with boot.efi - Netkas offers a similar solution for the Mac Pro 1,1), but that doesn't matter. 64 bit applications will still run in full 64 bit even with the 32 bit kernel.My 2006 Mac Pro is artificially obsolete by Apple.
With OS X:
I can't run Snow Leopard's 64bit kernel.
I can't buy any current video cards.
Games run like crap in Mac OS X (due to bad ports)
Video cards I completely agree with you on. I think Apple should rethink this as a bare minimum. You bought the M-P based on it's upgradability, and not being able to change the graphics card to todays technology quite frankly sucks.
As you say games run like crap because they are bad ports of Windows games.
With Windows 7
I can boot and run true 64bit Windows 7 with no restrictions.
I can use any PCIe video card I want.
I have a huge selection in games that run 10x better on the same video card. (no stutters at all with max settings on).
It pains me greatly to say that my computer is a better PC than it is a Mac. I hate, hate, hate Windows, so I'll keep using Mac OS X, but it's sad that Apple had to go and stop producing graphics cards or firmware updates to keep these machines going strong.
Anyone else coming to this sad realization? Thoughts?