I believe you're right about the driver. I have an rt2500usb (Belkin F5D7050) that was unusable. I really thought I had wasted my money. I could be two feet from the router and not connect. I did some googling on the subject, and it seems this chipset/driver combo is really flaky.
Two days ago I found a new Windows driver package on the Ralink support site, which I downloaded and installed in Windows. Then I grabbed the driver off my Windows partition and installed it in Suse with ndiswrapper. The connection is ROCK STABLE in both OS's. In fact, I'm wireless right now
and loving it...
Try looking on the Ralink site. They may have something that will help...
Timothy.