Looking at the website, the only difference spec. wise is that the se2 has a coaxial spdif connector, as opposed to the optical connector on the SE PLUS.
The website overviews also mentions the SE2's Dual Channel capability on the SE2, but not on the PLUS?? The specs are probably more a more reliable source.
I opted for the PLUS as a home for my Q9550 and 8GB of Corsair DHX DDR2 800 memory, all seems well so far although I will need to plug in the values for the EPD DDR2 timings as this Mobo (as many others) only used the SPD settings. There are around 15 DDR2 settings if you go the manual root.