If you're going to be playing around and learning, I'd advise at least one extra partition for /home. While playing around, you might break something, you might run into an obstacle, or want to change distros in a couple of months. If you have a separate /home partition, you can keep your work and config files without having to mess around with backups, and just replace the system partition. Also, 20GB should be plenty for linux to start with - the system itself isn't likely to grow beyond that. If it was me, and I had no other use for that 28GB drive, I'd make THAT my /home and use the other drive for the system+swap.
BTW, you probably don't need anywhere near 1.5GB of swap - it's just a waste of disk space. There are some recommendations for using RAM*2 for swap space that are just superstition nowadays. If you had <64MB, then it was a reasonable rule. Now it's just silly.