I can say from experience that Windows 7 is a fantastic netbook OS. Since its very first demonstrations Win 7 has been shown running on netbooks. And yet, actually loading Windows 7 onto a netbook is a highly inconvenient task. Netbooks have no CD or DVD drives (disks are so last century) so in order to load Windows 7 you have to either get an external drive, or use your desktop to load the files onto a flash drive and get them over to your netbook.
It's not an agonizing process by any means, but it is a lot more of a pain in the butt than just slipping a CD into the drive. That, however, could change very soon. Cnet just reported that Microsoft is considering selling Windows 7 loaded onto thumb drives. The final decision hasn't been made, but I can't imagine Microsoft not doing this. Netbooks are a huge and growing market, and a thumb drive pre-loaded with Windows 7 would sell like hotcakes.
There are other options of course. Microsoft could just sell a direct downloadable version of Windows 7. Cnet also notes that they could offer an update service through Best Buy's Geek Squad. I happen to think that would be the worst way Microsoft could deal with this. Some of us want to be able to reformat ourselves, without having to take our machines in to Best Buy.