well, the thing is the ones that guy did(ok didn't read whole thread) but sound like he just got an ES cpu and did test's himself. all the "done with intel there on system they set up" previews don't show anything like that kind of boost. you got it spot on with gpu limited games there really is very little gain if any from a great cpu. i do a lot of stuff other than gaming and find a faster cpu very beneficial so will get one. i run a benchmark or two , 3dmark and maybe some superpi purely to just check a new install is working as it should be, i don't tweak the hell out of anything or post my scores up in forums, if i did then i'd get a conroe for now
the main thing is, if you need a new system(on something old) then theres really very little reason not to go conroe as they pretty much are faster at every single price point (well in a few days ). as for upgrading from a 939 system just for gaming, you won't notice any difference so i wouldn't do it just for that.
the other thing to say is, out of most poorly coded games, its generally the gfx side of thing thats poorly done. overuse of lighting, or poor use of effects when it doesn't really change how things look, as in, there can be too much of a good thing.
if thats your current system set up in your sig then, well, let us know what your budget is and i'll tell you where's best to spend the money. it all depends, due to the board you have if you said you had £300 i'd normally say grab a x1900 as that will easily make the biggest difference with your set up, but you're on agp. the 7800(i think) agp is so overpriced because its the only agp high end card you can really get so IMHO is a waste of cash overall.
if you had say £500 i'd say get the £150 conroe, a £70 motherboard, drop £70 on very cheap gig of mem and then find maybe get a x1900gt if you can find one(seem to be very rare in the uk) or a 7900gt i guess. also guessing after release(within a few days) the cheapest conroe will drop a lot, its supposed to be $167 or so, how that equates to £152 i have no clue.