Confused about how to connect front USB

[ss2]

Every time I try to put a case together with a MB - this question comes up.

The connectors from the case (front panel USB) to the MB have 4 pins together and 1 extra.
The connectors from the case show these on the pins.
USB1+, USB1-, VCC1,GND1 A and the spare is GND.
USB2+, USB2-,VCC2, GND2, and the spare is GND.

The MB has 2 sets of onboard USB headers. USB1 and USB2. Each of these has 2 rows. I row has 4 pins and 1 row has 5.

The MB is an MSI 945P Neo3.

I have never been able to figure out how to hook up the pins to the MB. I know this is really a dumb question and should be easy to figure out, but when I have more spots to put pins than I have pins, what goes where?

I bought the MSI board because I had always thought there documentation was so good. It probably is - I'm just brain dead on this. If someone could explain to me what pins get connected to what I'd really appreciate it. Do I use the extra GND connector? Do I use only one set of 9 or do I use one row on each option?
If the connector from the case to the board had 9 pins with one missing I could understand it better. I get the part about where the VCC is (whatever that is), but pin 9 shows "key" and number 10 shows "USBOC". I have no clue.

One other thing that isn't clear. The paired memory. I have a total of 1gb corsair DDR2. Do I put 1 DIMM in each colored slot or both in the same colored slot? I was trying to find the packaging for the memory since I'm removing it from an INTEL board that I'm currently using. Other than the size of the memory, I'm sure what it is. I know it's DDR2.

I used to be able to put this stuff together without a problem. Either it has gotten more confusing, or I'm just getting too old to figure out simple stuff.

thanks,
Susie
ssarge(remove)@owc.net