Maximum PC

Finally looking to upgrade my trusty WRT45G to a Wireless N router, but had a couple questions and looking for suggestions on what to get.

Ive been reading a bit about "Dual Band" routers, but I still havent been able to determine something. If I have devices connecting at 802.11g and other connecting at 802.11n, do all routers kick everything down to "g" speeds assuming all devices are connected simultaneously or are there some routers that can handle both speeds at once?

Basically Im looking for something as close to (or even under if possible) the $50 range. The only features Im concerned with are (of course) decent speeds, the possibility to load dd-wrt and would be nice to have gigabit ports. I dont need NAS functionality, USB ports or the ability to run torrents from it.

Any suggestions are greatly appreciated!

Yes and No. Dual Band have two seperate transmitters (granted n can have more) one trasmitts in 2.4Ghz the other in 5Ghz (think of them as two seperate APs). So a G device on 2.4 will have no effect on a 5Ghz device.

Now if you are running a N device on 2.4 then yes a g device coming onto your network will slow you down. The router will enter into protection mode and dumb down the management and control frames. However your data frames will stay at the higher speeds (so N device get N data frame speeds and G gets its data frames at it's G speeds). You can also turn off protection mode and not support G devices, but that can cause more collisions to happen and in a home market that will be highly likely. Also most of your speed in N comes from using 40Mhz wide channels in the 2.4Ghz specturm you can for get about it in most parts of the world and will have to stay at the 20Mhz wide. Now N at 40Mhz wide in 5Ghz well that's a different story (this is where the true speed and performance of N comes into play). Also take into account what security you have to use with your productss. If you run N with anything other than AES/CCMP you revert back to legacy data rates of G.