A couple weeks ago I successfully installed Windows 7 on my Dell Mini 9 netbook and in the end it's only using up about 600MB, which is one or two hundred more megabytes than XP, which confirms reports about it being lighter weight than Windows Vista, and suitable for netbooks.
Unfortunately, a feature introduced in Vista remains in Windows 7 that could pose a problem to the lifespan of these netbooks. This feature is a Scheduled Task that is preconfigured to defrag the primary hard drive every Wednesday night. This is a good feature for "normal" hard drives, but is bad news for SSDs. Defragmenting a SSD (Solid State Disk) drive is hard on the drive. A normal hard drive can handle millions of reads/writes. An SSD drive is limited to only tens of thousands of overwrites per sector or data bit. Furthermore, SSD drives have zero (0) seek time, so defragmentation is entirely pointless on an SSD drive. If the hard drive is significantly full and the files are often fragmented, the defragmentation process will do a lot of damage to the SSD drive.
I reported this here:
Unfortunately, Microsoft updated the Status on this to "Won't Fix" and commented that they might look at it in the next version of Windows after Windows 7.
Well it's not worth fighting about, but at least be aware. If you do install Windows 7 on an SSD-based netbook or other SSD-based computer, just be sure you fire up the Task Scheduler administrative tool and track down that scheduled task to disable it.