You dont need all 4 CDs. I think you'll get a good base install for a desktop in the first 2. I think you should only need disk 3 or 4 if you want to install some of the server options (mySQL, Apache, Samba, etc).
Two other things you may want to check out:
http://dyne.org
http://lamppix.tinowagner.com/
These sites allow you to download and make 1 CD that you can boot a PC from. You get a lite version of Linux to play with. No need to install anything. Everything runs from the CD. Tons of free sofware to play with. When you are finished, remove the CD and reboot the PC. The PC returns to the old OS.
Dynebolic is probably the cooler of the 2. You get tons of Audio/Video software on that one. I saw a presentation on it once and was very impressed of what it could do. I have a copy of the disk, but have been too darn busy to do anything with it.