You may find that they won't school very well in just a 5g... I don't know, but a 5g isn't all that big to try and do a school of neons so you may not get the effect you are going for.
The bigger the tank you have, the bigger the school you could get. And, the bigger the school, the more interesting they are to watch.
I think I remember reading that neons aren't very hardy fish. You should read up on cycling, if you haven't already. Neons may not live through the cycle, so you should look into doing a fishless cycle. There are sticky's here in the beginners section that tell you everything you need to know about cycling your tank. Then, if you have any questions, just ask!... Welcome to The Tank! *thumbsups