I have to create a fair few user accounts from time to time, normally on a bulk basis. Ive found this formula in excel to be very handy as more often than not the network has some sort of SOE that requires a certian sort of format for the username. eg John.Smith (firstname dot lastname)
The formula is quite simple, broken down its =Cellnumber&"."&Cellnumber
In the example below you can see B1 contains Tyler and C1 contains Caffell so the formula in this example is =B1&"."&C1 which outputs Tyler.Caffell
Once you have your usernames setup the properly you can then save as CSV or whatever format you like and import into AD.