It seems to me that your partition sizes are not the best choices. For a normal installation, your root(/) partition doesn't need to be so large. I am running openSUSE 11.4 with the defaut root (/) size proposed by the partitioning scheme at the time of installation and it is 20GB. The partition has filled up with time, but now still has under 6GB of files on it.
For my system with its 4GB of RAM there is a Swap partition of 2GB. If you want to use a boot(/boot) partition, it usually doesn't need to be more than 10MB, but you can make it 20MB, or 512MB. It is /home that will contain your data files and it is there you have use for the balance of your 500GB storage capacity.
If there is some reason that you need more space in one of the directories under root(/) then you can make separate partitions for /var, and the others. This shouldn't be the case unless this is a server.
You might get an idea of what your linux distribution thinks is a reasonable partitioning scheme by booting the installation CD/DVD and running the installation until you get to the suggested partitioning layout, looking and making notes. You can then cancel the installation.
If you want to gain experience in using the GParted partitioner found in most linux distributions, you can download a copy of PartedMagic and practice with it.
If you do not have any experience with partitioning, you need to make a Backup
of all your important files before you do anything else!