9800 GT Choices

Hello, I'm looking at purchasing the best graphics card for around 200 dollars, maybe more, that I can find and that seems to be the NVIDIA 9800 GT.

I know what both core clock and memory clock are important for a graphics card but how much of a difference do both make? My exact problem is this.

I'm looking at an XFX 9800 GT (600 Mhz core and 1800 Mhz memory) and an EVGA 9800 GT (663 Mhz core and 1674 memory clock).

Is the extra 63 Mhz core speed on the EVGA worth losing 124 Mhz on the memory speed?

And do you think that the 9800 GT is the best for about 200-250 ish?

Thanks in advance, Patrick Osborne