I am usually more of a KDE person, but I have really been enjoying the Ubuntu Netbook Remix on my Dell Mini 9. Everything works great except for suspend when there is a mounted SD card in the card reader.
When there is a card mounted, closing the lid or suspending from the menu hangs the machine requiring a hard reboot to fix. There a bug report on Launchpad for this issue, but it seems that little progress is being made. I really hope this issue is resolved for 10.04 or before.
The 8GB internal SSD is sufficient for now, but it would be nice to have a card in the reader permanently for extra space.