The FC4 install should guide you through the process of partitioning and installing it easily.
It has a partition manager built in and will ask you during the install what you want to do with your hard-drive.
You can make the / partition around 4-5GB and /SWAP between 256MB and 1GB depending on how much phisical ram you have and /usr or /home the remaining space for your movies an stuff.
Hope that helps!