There's nothing better than WinXP for mini notebooks, netbooks, and even laptops.
Windows 7 is still heavier than XP. Many companies rely on software written for XP, and no say if it will work with 7.
If I run a quick batterytest on my netbook,
XP gives me roughly 3,7hours of battery.
Windows 7 gives me 3,3 - 3,4 hours of battery.
Windows Vista gives me 2,7 - 2,8 hours of battery.
Netbooks and mini netbooks are not really made for other than basic and +4year old games running DX9.
Running Windows 7 will decrease battery life, compared to XP for regular office jobs and internet tasks, (especially with the pre-loaded IE8 which is much heavier than IE7).
Windows 7 has more background tasks running, more system resources taken, unless you set it to display Windows 9x/NT/2000/ME theme, the Win 7 theme utilizes more memory, GPU, and CPU to load than XP.
Really, I see no reason why you would even say Windows 7 is THAT superior, just because it was released 6 or something years later...
I mean, Windows7 is still not released. At this moment XP is still KING of the hill apart from extreme gaming on DX10 games.