depends on what you want to do and what you are putting it on. If you are just throwing it on a small server, then ubuntu 6.04 would serve you really well. Compared to other flavors I've worked with (including Fedora 5 and several versions of Suze), it is the most painless to work with. 7.04 (Fiesty) is a little better if you want to use it as a desktop environment or are for some reason require wireless support, but for a strict server, 6 would work perfectly....especially since the server release can be installed as a LAMP server directly off the CD.