getting more ghz

2nd Best bet is a CPU (and probably Motherboard and RAM too if current is inadequate to support CPU) upgrade like I did not too long ago. This is expensive.

Best bet is to buy a DC since it's a fraction of the price and runs game flawless of course.

I agree, it is probably best just to get a real Dreamcast console. You can get a pre-played one for cheap. As for what speed of processor, I’ve read Chankast runs games nicely with a processor above 2 GHz.

Just correcting your termniology.

Ghz is the speed rating of a computer's CPU, you can't "get" more out of it (unless you overclock, but I won't get into that).

Now, to make Chankast run faster (as well as any other type of program), purchasing a faster CPU would be your best bet (or perhaps purchasing a new computer if you're not familiar with the internals). Any video card past a Geforce 3 should be plenty as far as video requirements, emulation mostly is heavy on the CPU.