I am customizing a PC and I am not sure about a few things. If anyone could help me in making some decisions that would be great.

The motherboard will have a FSB of 1333MHz if its an Intel processor or a FSB of 2600MHz if its an AMD processor. I am not sure which brand of processors is better, Intel or AMD, and what price is suitable for my NEEDS. I am looking to play games and use the computer for surfing the INTERNET and doing work for school on it. I multitask a fairly high amount of the time and have multiple applications running a good deal of the time. What would you recommend?

Processor:
Intel Cor 2 Duo E8400 (3.0GHz, 6MB CACHE, 1333MHz FSB)  $169.99
Intel Core 2 Quad Q6600 (2.40GHz, 8MB Cache, 1066MHz FSB)  $189.99
Intel Core 2 Quad Q8200 (2.33GHz, 4MB Cache, 1333MHz FSB)  $219.99

AMD Phenom X4 9850 Black Edition, UNLOCKED 2.50GHz, 4MB Cache, 2000MHz FSB)  $184.99
AMD Phenom X4 9950 Black Edition, 2.60GHz, 4MB Cache, 2000MHz FSB)  $194.99
AMD Phenom X4 9750 2.40GHz, 4MB Cache, 1800MHz FSB)  $229.99
AMD Phenom X4 9600 2.30GHz, 4MB Cache, 1800MHz FSB)  $239.99

Memory (RAM):
I am deciding between two speeds of DDR2 memory. Is there a noticeable DIFFERENCE in performance between PC6400 (800MHz) and PC8500 (1066MHz) memory. Is it worth the money to go with the PC8500 or not? I was told there would be a bottleneck with the PC8500, is this true as well?