hi, i was wondering what my 4550 1.8ghz computer can go up to.

i was on here before and some said i can go up to 3.0ghz.
so i was planning on going to a 2.8 but then i heard mine can only go up to a 2ghz?

so can some one really help me?
thanks

can some one tell me if this processor would fit in my pc

Intel Pentium 4 2.80GHz 533MHz 512K 478 pin CPU OEM

thanks
hope to hear soon