The following should be of interest:
http://www.firingsquad.com/hardware/geforce_8800_gtx_gts_amd_cpu_scaling/page10.asp
Basically you will see far more of a boost (in games) from a GPU upgrade than a mobo/RAM upgrade. As you can see, in FEAR at 1600x1200 a 3800+ with 8800GTS beats an FX-62 with x1950xtx. OK so a conroe setup is going to beat the FX-62 but even so the fact remains that most games are GPU-limited at the res you are talking about (1680x1050) with AA+AF.
While traditionally I have tended to built 'balanced' systems, with 'good value' highly overclockable components (mobo/cpu/ram/gfx), I've come to the conclusion in recent times that often the best way to get top performance in games is to get a very high end gfx card and then scrimp elsewhere, buying el cheapo RAM and a relatively low end cpu. Spending an extra £100 on the gpu (say a 8800GTS instead of a x1950xt) makes far more of a difference in games than an extra £100 on the cpu (E6600 instead of E6300). Likewise while some high fsb/low latency RAM will give you a few percent extra, it doesn't justify shelling out an extra £50+ more which you could have used for a better GPU.
It's one of the reasons why I'm still using a Venice 3000+, but with a relatively modern GPU (7900GTO). I've upgraded my gfx, but I can't see myself touching the mobo/cpu until a new groundbreaking tech arrives, or Conroe drops down to proper bargain basement prices (say £250 all-in for a decent mobo, 2gig DDR2 AND cpu)
