ya the two chips are neck and neck, basically offer the same performance. The PR rating is sorta out of wack for the new socket 939's. The 3400 and 3500 are both 2.2ghz chips and offer nearly the same performance.
its interesting that AMD skipped some numbers and made the 2.4ghz chips the 3700 and 3800. Not only did they make the 939's even numbered, but they skipped the 3600 entirely.
Its strange.
2800 = 1.8ghz 512 cache
3000 = 2ghz 512 cache
3200 = 2ghz 1mb
3400 = 2.2ghz 1mb
3500 = 2.2ghz 512kb DC
3700 = 2.4ghz 1mb
3800 = 2.4ghz 512kb DC
If the pattern after 3400 would continue the 3700 should be the 3600 and the 3800 should be the 3700. Even then the difference between the socket 754 and 939 is not "100 virtual mhz" its just a few small percentage points with the socket 754 sometimes doing better.
Looks to me like AMD is over estimating the PR because they know intel cant release a 3.8ghz chip.