Issue with Laptop Graphics Performance (Low SM2.0/3.0 Score)

So I've had an Asus G71Gx (17" laptop)since it came out in '09 and I've noticed a serious performance drop recently.

I took the bottom panel off to expose the CPU/GPU to my notebook cooler and so that I could overclock to sort of see if that would help things. Temps have been lower than usual, but performance is still lower than before as well.

I originally thought it was the CPU, because the games that were showing performance drops were so CPU-intensive (WoW, Rift mainly). However, I ran a couple of 3Dmark 06 runs, and the difference in the scores I got almost 3 years ago and today is in the Sm2.0/3.0 Scores. The raw CPU score is identical.

Overall: 3Dmark 06 June-09 - 10754 ----- 3Dmark 06 Today - 7377. Sm2.0/3.0 Scores are around half (2500) of what they were.

Basically, I'm running Rift (which is not the most optimized game) on low render mode, with 20-40 fps walking around in the middle of nowhere.
CPU: Core 2 Duo P8700 @ 2.53 @ 2.89Ghz
GPU: GTX 260M

Old hardware, but is this kind of performance decline expected?

(This looked like the right forum, but if it isn't please move it).

Edit: I've had a few posters on another forum suggest this was an issue with Windows 7 and that I should reinstall it. Does this make sense?