rage3d tweak?

I just downloaded rage 3d tweaker and I wondering if "overclocking" my
Radeon 9000 pro 128 could do any harm, my settings are; core clock: 249.75
MHz, memory clock: 220.50 MHz. I wonder if it would do any harm and
depending on that, how much would be a suitable amount to overclock (I heard
that the card actually is underclocked, or that some pipelines are blocked,
I' not sure if that's just bs and thats why Im asking). Im also asking if
there are any other options in the tweaker that i could improve my speed and
game fps's with

Advise greatly appreciated