I'm a little confused here, if the user bought a nice dual band 802.11n router with a lot of bells and whistles, why wouldnt he want to get the most out of it, rather than staying on the built in G/N capabilities of his old Toshiba.
Yes, the router uses 2.4 and 5ghz simultaneous bands,
Yes, that creates two simultaneous streams, but
No, not all N cards or adapters can run off of and take advantage of both the 2.4 and 5ghz dual band routers out there.
You will need to get a new dual band adapter or PCI slot card to connect to both bands, and you decide which channel, channel width, and wireless mode from your router configuration.
IPCONFIG/ALL from your CMD prompt and then open up a browser and type in your Default gateway to access your router. Usually 192.168.1.100 or something like that. Understand that your distance goes down with 5ghz, but you get a cleaner band to play on.
Ask yourself, is it worth the money to get all of these components or is N at 2.4ghz good enough?