"Windows 7 x64 should recognize that RAM with no fiddling required.
If the BIOS doesn't recognize all 4 GB, there's no chance Windows will see it. It's possible that the reason they provide a memory support list is because the board is very choosy.
I would each of your ram sticks individually, to make sure the BIOS sees them correctly.
Now that I'm thinking about it, the SU guys are going to have a lot more experience with this."