"...or you could just use an external hard drive. If photos and those types of media are important to you and your wife, as they are to me, it might be time to invest in an external hard drive to back that data up to. From there you could just transfer the files over."
MacsOnAnabolics has nailed it.
If your wife's photos currently reside ONLY on a single drive, they are in danger of being lost!
You need to BACK THEM UP, and do it soon.
A low-cost and VERY easy way to do that would be to do this:
1. Buy one of these:
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=usb+sata+dock&x=0&y=0
(many items shown, all work the same way, pick one you like that is inexpensive and it will do the job)
2. Get a "bare drive" from the vendor of your choice (I like newegg.com for good prices and fast service)
3. Put the drive into the dock, connect it to the Mac, initialize the drive with Disk Utility (it will need to be initialized before you can work with it)
At this point there are two ways to go.
You can either "manually copy" the files you want (photos, etc.) to the docked drive, or...
Better yet, use CarbonCopyCloner (free) to create a "bootable clone" of the drive in the new MacBook. You will then have an exact copy of the internal drive, including the photos. And -- in an emergency -- you can boot from the docked drive, and "work on" your internal drive if need be.
ASIDE:
If both MacBooks have firewire, set up the old one for firewire target disk mode, hook it to the new one, and use migration assistant to "get the new Mac where you want it" before you create the bootable clone.
