Maybe it was because i was using REVWD in conjunction?
Also i did use Redimized, im also wondering, which order should I install World textures(textures in general)? Oblivion>DLC>Texures or Unnofficial patchs?
Actually nevermind, i didnt read right.
RAEVWD is murder. Well, if you use all of it, it can be. Especially in conjunction with QTP3, and a bunch of other hefty things. I should know.

FWIW, I also use an e8400 (but OCd in this case) on Win7 x64, with 4GB, and an HD5850 w/ 1GB. It runs everything I've thrown at it, including heavily modded Oblivion, but then, even though it's not the most hardcoe PC out there (by any means) it's no slouch either.
I would suggest
gradually adding such mods, and experimenting with settings (Oblivion's, and mods') until it's just right for you.
Also, check out things like Streamline, Obliviion Stutter Remover, PyFFI, etc.
edit: oops, missed a post that makes some of what I've said redundant...