Ubuntu XP dual boot comparison & changes

My original OS is XP, I finally installed Ubuntu on its own partition.
Ubuntu looks fine on a few trials, except that:
1. Documents saved in Ubuntu cannot be opened by XP, although all my documents from XP can be opened by Ubuntu. That limits my continuation of Ubuntu- If there are reasonable solutions available I have not yet found them. Help anyone?

2. Yes, I play games. Right now, Freecell. Using XP, I am at 4430, going up serially. (I have no solution for 1941). Ubuntu did not allow me to choose a number of my choosing. This limitation may apply to other items.

3. I must have XP as a dual boot, since I cooperate with my grandson, and my other younger grandchildren use my computer when they -often-come around.

4. What are the differences between Ubuntu, Kubuntu, etc. As a long-time Windows user, I like the GUI system, though I use the command when necessary. Preferences anyone?
Thanks
ezrab

"Kubuntu" has what is called a "KDE" desktop, "Ubuntu" is a Gnome desktop.
Just a matter of style and personal taste. Ubuntu is the more popular of the two. If you'd like to try a KDE desktop, you would be better off installing "OpenSUSE"
http://en.opensuse.org/Welcome_to_openSUSE.org

About Ubuntu documents not opened by Windows: All of Open Office documents can be saved as Microsoft documents. If that doesn't work, save your files as PDFs, which can be read in Adobe's Acrobat Reader.

I have Ubuntu and SUSE, and I really like Ubuntu because it has an easy interface, and it is quick and easy to install...it's usually up and running in 15 minutes.

For a good gnome based distro that won't crap out on you, go with Debian, for KDE go with OpenSUSE or Mandriva. Try to avoid Ubuntu unless you don't mind tinkering.