Hmmm this is a different scenario now. As always, MMO's try not to go above and beyond and use graphic engines that are cutting edge, considering the amount of action you see on screen, it's more affordable for them and better for the users to use slightly less graphical intense engines (Aion = Farcry, WoW = not demanding, Lineage 2 = Unreal engine). But that trend is beginning to change it seems.
This one will be best decided by you, but some considerations.
1. a 3870x2 with a low end allendale oc'ed to 3.2-3.6. You can always replace the cpu later if you want, but the crossfire will help for larger resolutions, although we all know the r600 architecture has issues with AA...the crossfire scaling is indeed fantastic. Hard choice.
2. Q6600 with a 8800 GT, the multithreading will help speed games along, and the rig will definitely last years thanks to the better CPU and quad core. But as these newer games come out, graphical power and multi gpu setups is becoming more needed, we wouldn't have mid range cards offering high end performance for no reason if it wasn't the case.
3. allendale and two 8800 GT's (unfortunately you'd have to go a nvidia chipset), oc the allendale, and enjoy. We all know nvidia has the better cards atm, even though crossfire scales better, nvidia has the performance crown, so it's still ahead. If you want to wait a couple moths or so, you could nab a allendale and 9800 GX2 on a p35/x38 chipset, the 9800 GX2 will be a BIG seller for intel chipset users. People want SLI, but not everyone wants a nvidia based chipset, the ATI crossfire on intel chipsets is a MAJOR factor in AMD/ATI breaking analyst predictions for their quarterly income, people are massing up on crossfire rigs, and with two 3870x2's and crossfirex drivers coming next month, it's a money maker for amd/ati.
So this is a toughy, Conan and the Witcher are multi-threaded (conan for sure, not sure of witcher)...Then a q6600 will be beneficial....Choice is up to you, if you want extremely high graphical settings, the extra graphical power might be a winning factor. You can always replace the CPU later if you want. The choice is yours man, just trying to offer some insight on possible solutions. All sound good, but do keep in mind Nehalem is out at the end of the year in the extreme edition flavor, at the end of the year, all platforms are dead. Nehalem requires a new socket and new motherboard chipset. So it actually favors you to get a two card setup (or a dual gpu card such as the 3870x2/9800gx2), and save your money up for a nehalem board and CPU when the midrange comes out early Q1.
Keep in mind, the Nehalem performance gains will be massive, C2D to Nehalem is said to be even larger in performance gap compared to Netburst to C2D, we all remember how massive that was, so it has a lot of people VERY excited.
What do you think? Offer your concerns and i'll try to help you out on your choices.