hundreds of thousands of people have modded their ps2's. I'd suggst doing lots of research on it first, find some contacts and get some suggestions. Join a message board that deals directly with that stuff.

2 main reasons why.
1) It's complicated. It's not always drop in a chip and play games like usual. There's sometimes more things that you need to do.

2) It's almost always highly illegal. Mod chip sites get shut down left and right and there are usually authorites watching sites and groups like those all the time. Watch your self and educate yourself about the risks before jumping into it.