"But, first and foremost, remember that these are test releases, and are likely to still have significant bugs, omissions and various quirks in them. They are not intended for use on production systems!
"Ubuntu 9.10 Karmic Koala Alpha 3: This is probably the one that you have to be the most careful with, because they are changing the default bootloader from legacy GRUB to GRUB 2 (aka grub-pc), and that is a big, big change. If you don't have your system set up for multi-boot, you might not even notice the difference."
