ATI Mobility Radeon X600 continuing problem

Question

Don't know what "modding" is...
Don't know how set up video memory from 256 to 128Mb...
Which Catalyst driver version do I download?...

As you can see, I'm not as tech savvy as you, so I'd need some help. Any chance you can walk me through it step-by-step? you can send me an email directly to [e-mail] if you're up to it, thanks!