My XPS m1730 is not up to par

I'm getting quite fed up with this computer, as no matter what I do, there's always something wrong with it. I thought for the longest time it was simply having 32 bit Vista that was killing my system, and it partially was, but many of the problems I had before are still present on my Windows 7 set up.

My 3DMark score was roughly 8700, which is ridiculously low considering my set up. I've tried disabling PowerMizer, but it isn't present in any of my video registry keys, and neither is PerfLvlSrc or whatever that is called.

Annnyway, I bought the top of the line XPS m1730 when I bought mine, and it is DEFINITELY not running the way that I want it to.

The CPU randomly clocks down, whether it is hot or not. I had Dell replace my motherboard and my heat sink, and I spent 3 hours on the phone having them ask me if I had updated the BIOS instead of telling me why I can't control my clock speed on my CPU, even with the power settings, the BIOS, disabling programs that don't exist, etc etc etc. I've spent months trying to find out what's wrong, and I never post in forums, but I give up. I really just want the computer I paid for. There's probably some really simple thing I've been overlooking, so any ideas would helpful.

My system specs are as follows:

OS: Microsoft Windows 7
System Type: x64-based PC
Intel(R) Core(TM)2 Extreme CPU X9000 @2.80Ghz (I sometimes overclock this to 3.0Ghz, but I stopped doing it to 3.4 because all it ever did was overheat)
Bios Version: Dell Inc. A10
SMBIOS Version: 2.4
Installed Physical Memory (RAM): 4.00 GB
Total Physical Memory: 4.00 GB
Available Physical Memory: 2.89 GB
Total Virtual Memory: 7.99 GB
Availabe Virtual Memory: 6.57 GB
Page File Space: 4.00 GB

NVIDIA GeForce 8800M GTX x 2 Running in SLI
Driver version: 186.81
Stream processors: 96
Core clock: 500 MHz
Shader clock 1250 Mhz
Memory clock: 799 MHz (1598 MHz data rate)
Memory interface: 256-bit
Total available graphics ... 2303 MB
Dedicated video memory: 512 MB
Shared system memory: 1791 MB

I don't know what else there is to list, I just wrote everything I saw that looked moderately important, if you need any more info, feel free to ask.

Heres one last comment on the processor speed, I ran the 3DMarks test, and got a terrible score, around 8700 (Terrible considering my system specifications) and I decided to see what it thought my system was, and when I asked it to show me the system info, it said this

Internal Clock: 1.8 GHz
Internal Clock Maximum: 3.0 GHz

Whyohwhyohwhy..

I just want my computer to run at the level it should, so please, tell me what I ed up, etc. Thank you for your time.