I'm comparing the two 15" MBP configurations and trying to understand the $500 difference. I basically see there are only 3 differences: 1) 2.2GHZ vs. 2.4GHZ 2) 120GB HD vs. 160GB HD 3) Ge Force 128MB SDRAM vs. GeForce 256MB SDRAM Is there some other reason why the mid-level line is an extra $500? The HD upgrade is at most $75 (that is what Apple charges) and the 2.2 to 2.4GHZ would have a minimal impact as well. Is it really worth paying all the extra money for an extra 128MB of SDRAM? Do you also get something else or does it drastically impact performance? Any thoughts would be appreciated. BTW, I know a lot may change after Jan 15th, but I'm still trying to understand the current differences. Thanks.