This article mirrored my experience. I recently upgraded from a A64 3200+ (single core, 2Ghz), 2Gb DDR400 + 8800GTS 320mb (XFX XXX edition) to a E8400 (dual core, 3Ghz), 4GB DDR2800 + the same GPU and I went from not being able to play a lot of newer games properly, to playing almost all of them at my LCD's default res (1680x1050) with highest detail settings. I knew the CPU was the limiting facter after playing Race Driver GRID (awesome game btw), didn't seem to matter which res I tried playing the game at, it still run badly. After the upgrade I now run the game @ 1680x1050 with all the settings at their highest and it's very playable, in most cases the game runs around 50-60FPS with some slowdown if there's a massive collision however that's the GPU and the limited 320mb memory I reckon. Another example was Mass Effect, after trying the game out on my old rig I was left very dissapointed as it run quite badly. In particular the Citadel level. was running around 15FPS no matter which res I changed too (well slight increases but nothing that made the game playable) but after the upgrade I finished the game (x2) on highest settings @ 1680x1050 and the game ran around 60FPS for the most part.
I'm very happy with my setup atm however am looking into upgrading the GPU sometime within the next few months as I would love the play Crysis + Warhead @ 1680x1050 in DX10 (very high settings) as I had to play in DX9, 1280x800 with all settings on high. It still looked better than any other game out (even though the game is a year old) but I've got that 'it can look better' itch which I simply have too scratch
Am currently undecided on whether to get the 260+ or the 4870 1GB (with custom cooler of course), think I'll wait till after the holiday season. Sucks to buy anything atm anyways as the Rand $ollar sucks so badly atm (I live in South Africa, Cape Town) due to the recent financial crisis. 2-3 weeks ago it was 7.80 to 1 (R vs $) and now it's sitting at a insane 11.40 to 1 :-(