I have a laptop currently running Fedora, how can I dual boot it with Ubuntu?
If you drop an Ubuntu DVD in the drive, its partitioner will see your Fedora install and offer to shrink it to make room for Ubuntu.
One thing you could do is, if you have a separate /home partition under Fedora, is manually set the partition to be your /home partition in Ubuntu, so they'd share the same files and settings. If you're not familiar with partitioning, look around on the Internet for a guide; it's not that hard. Just make sure you have backups in case you accidentally nuke everything.
The bootloader configuration should be mostly automatic, too. Ubuntu will detect Fedora and allow you to select Fedora at boot time, just like you can with Windows. All in all, it should be pretty painless.