So, in 10 years there may be some compatibility?
Lets get ready for 2 Petabytes of Ram!

But you will need at 64 bit version for Exchange 2007 in any case. So I doubt there will be a lot of people getting them a 32bit if they want to run Exchange 2007

Didn't someone post on this forum, that the new Opterons will be able to handle 128bit address registers? Not that we need that yet .. I am just so glad that Crytek made Crysis a 64bit game!

...or run a background render. 

My build right now, probably around 650 bucks is what you'll spend on it.
Can run crysis on low with good frames, but I'll give a better vid car suggestion.

Dual Core 5600+
eVGA 7950 GT KO Superclocked. (Sub this out for an 8800gt, it's only like 160$ right now)
2 GB of RAM (G.Skill)
Some 50 dollar motherboard. MSI. I'll get ya the link if you need it.
120 GB HD (Being replaced)
850 Watt Rosewill power supply. Thing is kickin.
Some no-name CD Drive

There ya go. That will run Crysis with decent frames on high (singleplayer) and medium (multiplayer).

AMD still has a strong foot in the door for server market share and "supper computing.". And I dont think any one would plan on using an 8-core 128-bit proc on a Windows OS. There will be lots of compatibility with people who write their own apps specifically for those procs and prolly their own OS. Thats who AMD has in mind when making these chips.