overclocking... Options

[Maccabee]

I need your help.
I have a 2.2ghz intel celeron procesor.
I was suprised by how many ghz though cause it came with 128mb ram. but it currently has 500mb ram.
Its prety slow and laggy running ubuntu and i want to speed it up.
using overclocking.
How can i do this safely and whats the how high should i overclock it or whatever. It has some 10 yr old crappy loud fans. So the cooling is prob pretty bad.
Should i open it up? O and this computer is ancient so im not to worried if something goess wrong.

[Maccabee]

Actually I dont think im gonna try and make this computer better.
Its so old and almost every driver has some sort of problem.
The video cards and graphic drivers or whatever are old and need to be replaced.
But i think im gonna start my computer setup.
I finally decided that id rather have a pc than a imac cause with the same 1200 it costs to get an imac i could buy 2 monitors have tons of ram and hard drive and buy leopord!

Edit:
Im not totally sure but i think my computer thinks i have only 128mb ram.
When i check like in linux it says 500mb but in bios it says cahe 128?
I think my ram sticks arent matching. could this be a problem? I think im mixing like a 256 with a 128. would it be faster to replace the 256 with the old 128? Im pretty confused right now. I think ill open up my computer and pull out the ram to check.