What is Multimedia Instruction MMX SSE SSE2 SSE3 SSE4 EM64T

[Guest]

Hello,
I'm torn between SPEED (3.0 GHz) and Multimedia Instruction MMX, SSE, SSE2, SSE3, SSE4, EM64T.

$50.00 price difference and 0.2 MHz differance.

 

[randomizer]

Well just about every modern processor is going to have the first 4 and the last (or the equivalent, AMD64). What are the two processors that you're looking at and what do you plan to do with the computer?