Blu, just make sure you partition your hdd. Split it into 2 parts where the first is 60GB (yes, you convinced me ) and the other gets the rest. You will be thankful should you run into trouble later.
You can do that with the Ultimate Boot CD. Keep in mind that you have to format again. The boot CD has a tool for that too, or you can again use Ubununtu for it.

Also I wonder, why does Win7 detect the HDD when it's formatted but not before when it has a partitioning/formatting tool of its own? Somebody has a theory on that?

No clue why that should happen. It should see it either way, after all you first have to see the drive before you can tell what's on it, and formatting only changes what is on it.

Personally I would've just posted on the mobo's support forum, there are lots of crazy-experienced people on there, as well as company representatives that can get actual new knowledge and fixes available for newly reported problems. Depends on the company too, though, I guess.