Overclocking a 2500+???

Yeap, if you set it to 9 x 200 the CPU will run at the same speed as the stock processor & at the same temps. There is a small possibility though that your CPU won't be able to run at 200MHz, but most 2500+ do. If you manage to boot your system at 9 x 200, then you can continue by increasing your multiplier until you reach a point where your system won't boot. Even then, you can try increasing the vcore voltage a bit (I consider going up to 1.7v on air safe) to see if you manage to get your CPU work at that speed. I know many people using their 2500+ either at 10x200 or 11x200 with no problems.