Hi Krick,
The 32-bit version based on 6.5 allows for up to 200 modes, so this was considered a possitive difference as compared to 9.3, but since we're using magic resolutions, this is not relevant any more.
As for its 64-bit version/6.5 counterpart, well I'd use this one only for the cards where it's strictly necessary. As a fact, this version was really hard to find because it was never officially supported by ATI. So I'd stick to the 9.3 version when possible.