Not that anyone's asked but I'm not a big fan of separate partitions for /boot, /home, etc.. I would create 3 partitions:
You can bind or symlink subdirectories in /Data to your home directory if you want to preserve all your Pictures, Music, Documents, Downloads, etc ...
is home inside / on a standard install? is this the equivalent to 'my documents' being inside 'C' in windows?
Here's the problem with a separate /home partition: it's not the equivalent of "my documents" in Windows. It's more like "Documents and Settings" plus certain elements of the Windows registry. So let's say you've just made a royal mess of your install and you figure the easiest way out is just to reinstall. When you do that you just restored some or possibly all of the things from the /home partition that caused the problem in the first place. A separate Data partition makes more sense to me. So when you reinstall or if you decide that KDE is the best option for you all of your data is preserved and none of your old settings will interfere with your new install.
There is no right answer here and I'm not suggesting that my way is the right way. It just reflects my own experiences over the years.