Am I missing something here? Or is Microsoft doing business as usual?

I bought an Acer 3690 notebook that came loaded with Vista Home Basic. I have read that the upgrade to Windows Home Premium would be discounted 50% to buyers like me? Not so it seems so far in my quest??? Microsoft had to know there would be thousands of us wanting to buy this upgrade. Yet I have not been able to find ANY information about how to do this??? All I can find is the full upgrade from XP, etc... about $150. or so.

So far it looks like I could load my legal (but never used) XP Pro onto the new Acer and buy a Vista upgrade for less money...

Anyone know more about this?
thanks, friend ~ Brick