Wireless N Routers, dual band, 5ghz, confused

I've been reading alot about the new pre-n routers but am still getting alittle confused on what it takes to have max performance on an n only network.

As I understand, draft n has a spec for each band, 2.5 and 5ghz.

Assuming that there will be only n devices connected to the router, as far as overall performance is concerned, do I need to have a router that has a 5ghz band?

In looking at the DLink 655 vs. dgl-4500, the dgl-4500 has dual band/single radio, so you can d: 5ghz mixed n and a, 2.4 mixed n g b or mixed ng, or mixed gb. (the dir-855 id a dual band/dual radio, but out of my price range)

I understand that at 5ghz you'll have less crowning of the frequency because of all the other devices and applications that run at 2.4ghz and that, that in itself would be worth the dual band router.

Just some information: Medium sized 2 story home (great coverage with existing g router), 15mb+ internet connection, mixed xp/vista boxes.

 

You need dual radio to run 11n and 11g at the same time. Currently single radio have to stop to run the other. With a dual radio you can have both 11n and 11g active at the same time and not interfer with each other.

5 ghz is has less traffic and interference, but being a higher freq it does not penetrate walls as well. So you will have a shorter range. With the 5 ghz they can use channel bonding and not have to worry about interfering with other networks.

 

I'm in a 2 story medium sized home using DGL-4500 11n 5Ghz. I have 20+ Wireless networks around me all using 2.5Ghz. I have had no problems with signal strength or interference. Lowest signal strength I have seen in my home opposite floor opposite side is 85%. just been up for a few days though.