PC Problems

So, I've dropped a bundle of money on my computer over the last year or so, and my current set-up is as follows:

Pentium D 915 CPU, @2.8 Ghz
2 Gigs of DDR2 667 RAM
eVGA GeForce 8800 GTX
Asus PN5-E SLI motherboard
Seagate 250 GB SATA HDD

I have liquid cooling for the CPU and GPU, and both never get above 45C, even under load, which is pretty nice.

My problem is, my performance sucks. Over the last six months, I've gone from XP to Vista 32-bit to Vista 64-bit, and my performance in games is just pathetic. For example, Oblivion barely gets me 30 FPS at 1680 X 1050 with medium-level details. Turning on HDR is like executing my video card. I ran 3D Mark 06 in XP, got about 5500 marks. In 64-bit Vista, after OC-ing things, my top score has been just under 6800. My cousin, meanwhile, with a generally inferior system, pushes 11000 marks.

I've OC-ed the CPU to 3.22 Ghz, and the RAM to 733 (As well as dropped the CAS latency from 5 to 4), but, because I'm running 64-bit Vista, I can't OC the GPU at all (Which in of itself is enormously irritating). I'm about at my wit's end as to figuring out what the problem is. My score has only gone up by switching to Vista from XP, so I really don't think that's it, but I'm sure I could be wrong. What do you guys think?

I've got 4 gigs of DDR2-800 RAM, at 4-4-3-12, on the way, too.

No amount of OC will make Vista run fast on a pentium D

>>1 your eye cant handle more than 30 under normal conditions... under intense stress (which can be caused by videogames) it might feel choppy though ..

emmm try refunding ur card and suing the manufacturer btw... and oc'ing ur anyway mega fast cpu wont give u much in terms of framerate btw

Heard Vista has terrible video drivers. Try XP 64. Make sure you have the right drivers installed (the geforce 8 ones, not the regular GeForce drivers).
I have an 8800GTS, 2GB DDR2 667, and a Brisbane 3600+ @ 2.8GHz (that Pentium D can probably do 4GHz, but suffers from P4-like levels of instructions-per-clock so try getting a Core2)

>>4
Forgot to specify: I have that setup and can run Oblivion @1280x1024 with everything maxed out. Framerates are high 40's to high 70's depending on where I am looking.

I suspected it was due to my CPU being a Pentium D. I think I'll wait a week or so and see how much I can get one of those new Core 2 Quads for.

Yeah, video drivers for Vista still suck (Though they're way better than they were six months ago). nTune doesn't allow overclocking, and Riva Tuner will say it's OC'ed my stuff, but won't actually do it. I REALLY hope they get that fixed some time this year.

That RAM came in today (It's actually 4-4-3-5). OC'ed it 960 Mhz, pushed the CPU even further to 3.39 Ghz, still rock solid for stability (Temps are still barely breaking 45-50 C under load!). My framerate in NWN 2 has virtually doubled, even with graphical details cranked back up. Oblivion went up about 10 FPS, haven't checked any other games yet. Still, I'm pretty happy about that.