dstiles - 7:43 pm on Apr 22, 2011 (gmt 0)
Go to the Ubuntu site (if you want a Ubuntu based OS). They not only provide downloads of the two latest versions of Ubuntu (the x.04 version is often preferred over the x.10 version) but they also provide a good Windows DVD writer to burn a DVD for installation.
You can install part or all of KDE on top of the basic OS - I use perhaps a dozen K apps and several gnome ones.
A week or so ago there was a thread that recommended using Mint - I recommend reading that and a few other threads here. I haven't tried Mint but it comes well recommended.
There are other Linux varieties that run KDE but Ubuntu seems to be popular and as a recent Windows user I find it works well for me. Actually, I still have to use Windows but mostly as web servers - I comment on that elsewhere in this forum.