I did a search, but no joy

[Thunderbolt56]

From a rendering perspective, I'm pretty sure it goes in this order:

1. GPU
2. CPU
3. RAM

If you have a stout GPU with as much frame buffer as you can get (I'd say 512 would be low-end by mid 2009), a good dual core CPU with lots O' on-board cache and 2GB RAM for XP, 4GB for Vista then you should be able to run most anything. Also, by mid-09, quad core CPU's will likely be more common with more games and code written to utilize all 4 procs whereas a good dual core is often superior in games right now.

To speculate as to what will be "acceptable" (being a relative term) to run BoB:SoW, then that's anyone's guess.

p.s. Monitor resolution always plays a part. Increasing the resolution places higher demands on your rendering components where lowering resolution lightens the load...in a nutshell.