I did a clean Win 7 Pro install at the end of Jan 2010 and it has transformed the NB100 into a usable device (under XP the performance was terrible and it cound not play YouTube or iPlayer videos.
Plase note you need access to another computer with a DVD drive as you need to copy the installation files and applications to a USB stick.
1. Upgrade BIOS on NB100 to latest version from Toshiba support website and download all the drivers for Win 7 from the site (sound, wifi, display, Intel matrix etc)
2. Create a bootable USB 4GB stick and copy across the W7 installation files/directories to the USB drive (Bootmgr must be in the root drive of the USB stick) - I used the following guide:
http://www.intowindows.com/how-to-install-windows-7vista-from-usb-drive-detailed-100-working-guide/
3. Copy all the files off the NB100 (documents, music, Outlook postbox etc)
4. Change BIOS to boot from USB
5. Insert USB stick and reboot
6. Windows will reload so you need to remove the USB stick for second/third etc boot or it will never move from the first part of the installation - but then put the stick in again as it contains the installation files. I did a clean install and formated the disk in the process.
7. Install all the NB100 W7 drivers, run Windows update, install AV programs (I use the free Microsoft secrity essentials which is light on resource needs)
8. When W7 install has finished use the USB stick to install programs eg Office by copying files from DVD to USB stick
9. Copy back files and postbox.
10. Run a defrag program - I use defraggler from Piriform (free)
You then have a fantastic netbook which has great performance (I only have 1Gb RAM) - I am staggered by how fast it boots and runs
People with a lot of data files might find it helpful to partition the disk at stage 6 and keep the OS and programs in a separate partition to reduce fragmentation as much as possible
The W7 battery management is also great and in low power mode I get 7hrs off a standard battery.
When I first thought of doing the upgrade I thought that I would probably need to reinstall XP as the NB100 would not have enought power to run W7 - how wrong I was.
W7 performance stats are:
CPU - 2.2
Memory - 4.5
Business graphics - 2
Gaming graphics - 3
Hard drive - 5.3
Aero works great BTW.