My Rayleigh Tamland, also about 5 years old, has Weinmann rims and used to have a spoke breaking problem on the rear wheel. I'm 240# and do overnights on rail trails, so heavy load on bad roads. The stock wheel was breaking the spokes at the nipples. After replacing a few spokes and getting tired of dealing with the crappy rear hub I finally upgraded the rear hub and put in a new set of Wheelsmith double butted spokes, but reused the rim. When that started breaking spokes at the J bends I bought a Park tool spoke tension meter to check my work, only to find the spoke tension was spot on.
At that point I got pissed, threw the Weinman rim in a recycle bin and laced up a Mavic A719 rim with Sapim double butted spokes on the brake side and Alpine III triple butted on the drive side like cyccommute suggested.
No longer breaking spokes, LOL.