I have been installing and tweaking the latest Kubuntu.org Linux (version “Edgy Eft” or 6.10).  So far I like what I see.  I have also changed over to a newer server - a Dell Dimension 2350 that runs at 2.0Ghz rather than the 450Mhz of my old server.  The hardware upgrade obviously adds more speed to my computing environment, but I have also found that Kubuntu 6.10 is also faster and better on resources.  Power consumption seems about the same (the P4 has some cpu throttling capabilities that may actually improve the energy balance, but to be determined yet).
I installed Kubuntu 6.10 on a 233Mhz desktop machine with a 2.0GB hard drive (as the master node of a test “Beowulf/OpenMosix” supercomputer cluster of similar machines I’ve been playing with, but that’s another topic).  If you’ve been following my posts and looked at my main web site (www.privateproductivity.com) you’ll find I used Kubuntu 5.10 on a 266Mhz machine with 3.0GB hard drive for the last creation of my web site, which was the minimal system I could get away with (you’ll also remember I discussed minimal systems are good stress-testers of an operating system).  So Kubuntu 6.10 provides faster operating performance as well as improved interface eye candy.  Microsoft Windows Vista will have some challenges.
My installation of Kubuntu also utilizes LTSP.org - so I can boot multiple thin clients into the server.  I do this because I have a tiny terminal in my Kitchen (shoved in a cabinet) to quickly surf the internet or look up the latest TV show guides without having to hibernate in the basement office.. I’m writing this post on this internet appliance).  This also allows other household users to access the server via other thin client computers around the house - they can run at ten times the speed and memory than native old hardware being reused.  The latest 6.10 is supposed to allow local (client) devices like USB thumb drives, sound outputs, CD drives, etc which 5.10 would only work to display content on the clients - I’ll see how that goes as I finish my installation.  Oh, the clients boot significantly faster on 6.10 than the older 6.06/5.10 versions of Kubuntu/LTSP as was one of the goals for the latest operating system update.

So if you’re not afraid to experiment (it’s low risk in any event) then download a copy of the latest Kubuntu.org .iso file and burn it to CD.  Reboot your system with the CD in your drive and you can take a test drive, then just remove the CD when done and reboot your system to be back home.  Do remember that it will run slower from CD than a hard drive install.  If you want you can do a complete installation to replace Windows, or you can make a “dual boot” system and allow normal booting into Kubuntu or back into Windows as needed.
Cheers!