How do I reload the Mac OS on a new MacBook Pro that comes without Mac OS X DVD? I just purchased the base model (i5/4gb ram) MacBook Pro 13' 2012 computer. The reason I purchased the base model is because I already had an SSD drive and 8GB of memory compatible with this computer.

Unfortunately, Apple does not give the Mac OS X DVD any more, they load it as an image on the hard drive.

Since I need to remove the existing hard drive and replace it with the new SSD drive, how will I load the Mac OS image?
Any computer that shipped with Lion or Mountain Lion has Internet Recovery, which is a very limited installer that downloads the full OS from Apple and installs it. To get into the Recovery mode, just boot while holding down commandR, and it will prompt you for the rest.

However you can also do a direct clone of your existing disk to your SSD, which will avoid having to download the installer (it's about 4 GB) or reinstall all your programs and data. You'll need an external enclosure to put one of the drives in. You can do this with the built-in Disk Utility tool, or a tool like SuperDuper (the free version of which suffices for this task).