Keep reading these forums and you'll find your answers ... in fact the howto you are following indicates the command for showing you the size of installed packages.

Sadly, i'm sure like most you want the answer now so here is a start:

- KDE and OpenOffice are huge, maybe smaller alternatives will suffice such as fluxbox and vi (now there is few hundred megabytes emancipated )
- Remove all games, cruff, and
- Depending on competency and dependancy on assistance you can always remove the man pages.