Just name the SSID on the wireless routers differently and you'll be fine.
Well, I got my N network up and running in fixed N mode. Fast and strong... very happy. I added a G access point for the droid. No issues, works great. However, I tried to connect the Droid to the N router and it works just fine. I thought this wasn't possible. I have a laptop without an 802.11n adapter and it cant connect, so it must be that the Droid CAN connect to N.