Quite frankly I don't see how you're running Windows XP on an 800MHz AMD Duron with 64MB RAM. Either way you probably don't know this because you lack GNU/Linux experience, but GNOME, and KDE are heavyweight window/desktop managers much the same as the Microsoft Windows XP window manager. Hence you need nearly as much RAM.
If you're looking to get speed out of a system with a lack of RAM then you need to use a lightweight window manager. Some good examples would be Fluxbox, Blackbox, and IceWM. Also since you're so in love with Windows then I suggest using IceWM as it will be the closet to your windows feel.
My choice would be with Fluxbox or Blackbox however because IMO I believe they are faster. You'll have to learn how to use them though. They are nothing like traditional Windows.
Debian is a fine distribution just switch the window manager.