I recently spent a good deal of time looking at the earlier betas of Windows 7 on a Dell Mini 9 netbook. The Mini 9 is an excellent small computer, and I've been very pleased with it and its native Ubuntu 8.04 Linux desktop operating system.
With the Windows 7 betas it was a different story. I found, in short, that Windows 7 required too much RAM and other system resources to run well on typical 2008 netbooks.
Like many such netbooks, the Dell Mini 9 is powered by a 1.6GHz Intel Atom 270 Diamondville CPU and has a gigabyte of RAM and an 8GB SSD (solid state drives). The display is not quite nine-inches-8.9-inches with the graphics pushed by the Diamondville's built-in 945GSE graphics.
The CPU is fast enough, but 1GB is not enough RAM by half for Windows 7 to show well. In addition, the 945GSE graphics are really not powerful enough for Windows 7's Aero interface. You can squeeze Windows 7 easily enough even into 8GBs of disk space, but there's precious little room left for data and applications.
That said, I did find that this latest build did fix some of the other problems I encountered with Windows 7. In particular, the networking troubles have vanished in this release. I also found in general that it was more stable.
Even so, Build 7100 made it even clearer to me that on a real netbook, a low-end, inexpensive system, Windows 7 is simply too much operating system for these small computers.