CAT 5e is superior to CAT 5 in that it has additional specifications regarding signal bleeding between cables and is able to handle higher bandwidth needs.. BUT CAT 6 is superior in transmission performance and should be used if you have true Gigabit needs in mind. That is... a Gigabit modem/router and ethernet card will be needed for the system to benefit from CAT 6 cable which is certiied to handle Gigabit. CAT 5e works with Gigabit speeds but CAT 6 is certified to do so..
Here's a link that might help with a basic discussion of the variables you are asking about:
Hope this helps.
I am running Verizon DSL on Vista want to buy a 50 ft ethernet cord need at Cat both ends are mail what is the difference between Cat 5 and Cat 5e