for what? the processors? well, for the processors im thinking that the operating speed will probably be a differnece, with the 3200 at 2.2 ghz and the 3500 at 2.4 ghz. as for ram, Charchris took da words right outta my mouth.
The 3500+ is faster than the 3200+, even though both of them are superb. BTW I think the 3400+ or 3500+ or maybe all of them won't support Dual Channel. It's because of the integrated memory contoller.
It should support dual channel, but in some cases with motherboard manufaturers such as Gigabyte, it won't run at the optimized speed. If you get 2 sticks of DDR400 and dual channel them, it may read DDR333 instead of DDR400. There was a link to that problem and it was regarding the limitations of the Athlon 64 processors. It will still work though, or should.