I'm sure the answer is right here but I am apparently too sleepy to find it after 10 minutes of reading excruciating details:
http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair
My guess is 5e but I'll probably just get 6 or 6a for the noise reduction features. More just curious than anything, price difference between 100ft of 6a or 6 is only like 4$.
Another thing that confuses me and I couldn't find a clear Google answer on, is what does 250MHz cable vs. 500 MHz cable really mean? I know 500 MHz can hold more data per second since it is higher frequency, but how does this relate to anything useful in terms of bits per second or which networking standards need which?