I've tested Vista on two netbooks, and it's never been good (not counting the Vaio P). In fact, Vista has been unusable in both circumstances. Then I loaded Windows 7 onto the Mini 12.
If you look back at my original review of the Dell Inspiron Mini 12, a 12-inch Atom netbook with 1GB of RAM, I liked the hardware just fine but complained that Vista was too slow to even be considered as the OS. The system often lagged when just opening the Start menu, let alone launching real programs. It, like Vista on most netbooks, was little more than a novelty—something to be chuckled at for a few moments before formatting and installing XP. So I loaded the mini 12 with Windows 7. What did I have to lose?
The experience is night and day.
With Aero deactivated (and actually, totally inaccessible after an auto-configuration installation despite screwing with the registry), the Start menu now pops right up (like it should), Firefox takes about 3.5 seconds to open (which is reasonable) and light multitasking is smooth enough. The computer is by no means fast, but it's reasonably functional. And I can use the system without pounding my head against the screen or loading an old OS. Keep in mind, this testing is just with 1GB of memory, not even 2GB.
The system still struggles a bit with both full screen Flash video and XviD clips. Heavily dropped frames remain a fact of life, and don't expect to fast forward through high quality content at will. But that's a hardware limitation that I can accept, or at least not blame on Microsoft. Intel, I'm looking in your direction now.
I loaded Windows 7 onto the Mini 12 as a Hail Mary maneuver, hoping to play with the system a little more without resorting to XP. And I have to admit, the results were pretty close to miraculous.