Re: Linux
Ubuntu has kde, thats good.
It is free yes, most packages are to.
I would recommend ubuntu.
I recommend you installing software like firefox and things trough the built in package down loader/installer.
If you aren't familiar with linux, it will be very hard to get it running good at first.
After you know the basic's like wich folders is what, you will find it very good.
Here are a few basic things.
Your filesystems lowest folder root / contains the following folders:
/bin Essential user command binaries (for use by all users)
/etc Host-specific system configuration
/home User home directories. This is where you save your personal files
/lib Essential shared libraries and kernel modules
/opt Add-on application software packages
/usr /usr is the second major section of the filesystem. /usr is shareable, read-only data. That means that /usr should be shareable between various FHS-compliant hosts and must not be written to. Any information that is host-specific or varies with time is stored elsewhere.
/var /var contains variable data files. This includes spool directories and files, administrative and logging data, and transient and temporary files.
/proc System information stored in memory mirrored as files.
Read up on it here