Are performance ratings of the cpu true? If not what should i overclock to?

I have a lenovo pc, it has 2ghz. Now when i go to system requirement labs it says it is performance rated at 3.6. What does this mean? Can i play games that require 3ghz because of this with no problems? If not i would overclock, i don't know what's the safest i should overclock to either.

The windows experience rating is a pretty vague rating that changes. It's mostly to give you an idea of how windows runs on your computer.

Your limit to running games on that laptop is going to be it's graphics performance, not the CPU.

A clock speed (measured in Hz) is very different from a rating assigned by a third party like Windows.

a CPUs clock speed isn't even indicative of performance anymore. There are so many CPU designs on the market that a CPU with a much lower clock speed can still be much faster than another one with a higher clock speed.
this started happening when computers started gaining complex architectures with multiple cores and multithreading and other technologies. The clock speed rating is only useful as a performance measurement when comparing 2 CPUs of completely equal design.
don't pay attention to programs that demand a specific clock speed. Instead pay attention to the type of CPU that they demand. If a program requires something like an Intel Atom or above, its going to be a fairly light weight program and just about anything can run it.
if it requires an Intel Core i5, its going to be a decently complex program that requires a lot more processing power. Something that demands an Intel Core i7 will be an extremely demanding program and is best run using top of the line parts.