Upgrading to a Wireless N Router

[blueice]

I am looking to upgrade my router to wireless N, however not all the computers in my household have wireless N cards. So while I understand it is backwards compatible, what do I need to do to the computers that have a wireless A/G card to get the speeds of wireless N? Is it a network adapter or do I need to replace the network card? Help???

 

[esd2000]

You have to replace network cards.