With Windows 7, you still have to setup the TV manually, by doing a Transponder scan, have you done that?

Steps to setup TV:
1) Go through usual 'Setup TV Signal' process...
2) Select region = NZ
3) Select postcode = 1011?
4) Select signal type = Satellite
5) Select more than 1 satellite = no
6) Select satellite = Optus D1
7) Select LNB = custom single oscillator
8) Select frequency = 11300

Once you have done all that, save and exit and ten go back into the Media Center Settings section and select the following:

1) Go into the 'Satelite Transponder Scan' setup....
2) Select single transponder scan
3) Enter the following:
- Symbol rate: 22500
- Polarization: horizontal
- Frequency: 12483, 12421, 12456, 12519, 12546, 12581, 12608, 12644, 12671, 12707, 12734

The frequencys you do 1 by 1, and that should find every possible channel, although many you will not need or be able to watch.

Entering those details, the?signal quality bar should turn green every time.

Hope that helps.