Microsoft's official retail price for Windows 7 isn't really the benchmark of whether prices will truly be lower. Even when a user buys a retail license, they they can often pay less than the official retail price. There are deals to be had out there. Here's one example: NewEgg is currently selling a full license (not an upgrade license) of Windows Vista Home Premium for $109, including a free upgrade to Windows 7. Microsoft's official retail price for the full version of Windows 7 Home Premium is $199; even an upgrade license is $119 retail.
The acid test for Windows 7 pricing is what happens with OEMs, who deliver nearly all Windows licenses. Will Windows 7 OEM prices be lower, or higher, than Vista? Notice that the low-end Windows 7 Starter Edition isn't even included in Microsoft's retail plans. You can't buy it. Even OEMs can't buy it unless they pledge to put it on wimpy hardware. By forcing computer makers to limit their hardware to qualify for Windows 7 Starter Edition, Microsoft can "firewall" their low-priced version and avoid eroding profits from the rest of the Windows 7 family. Based on this, I'm not convinced that Microsoft intends to give any ground on OEM profits.