Airtunes dropouts with Mac mini to Airport Express

I just got my Mac mini (2 GHz)hooked up to the airport express (wireless N version). I am having audio dropouts every few minutes - very annoying. Anybody have same problems? How do you guys fix this?

Right now I have the Airport Ex configured to join my network. The wireless router is b/g/n version. The airport in one room below the mac mini.

Change your wireless security setting WEP,WAP on main router, don't recall but airport express works better if memory serves on later security protocals, sorry dont remember witch i now use airport express connected directly to laptop only on a purist standpoint.