OK, FINALLY finished this! Read it and ponder...
In order to access the photos on her HDD, you can install her HDD in an external enclosure and connect it to your system with a USB 2.0 cable; if you choose to use this method, be SURE to SCAN her ENTIRE HDD with good AV / antimalware programs BEFORE you begin to transfer any files from one system to the other. Among other benefits, doing this will allow you to AVOID trying to have her HDD detected by your system BIOS, which can open a can of worms you don't want to deal with if her HDD is failing.
I realize that you might think that this is (or SHOULD be) a simple process and that you don't need to take these precautions, but you have no way of knowing if her HDD is infected with some program that will attack YOUR data. Furthermore, if her drive is failing, her data is at risk of loss at any time; booting an HDD puts more stress on the HDD components. If you put her HDD into an external enclosure, you reduce the stress significantly, so with a little luck, the HDD will survive long enough to transfer her files to a folder on your system. Once that is done, you can copy them to optical discs, or a flash drive, or whatever storage media you prefer.
You can buy an external enclosure for a reasonable price; I own seven, and just ordered two more (from Newegg) earlier this week. I admit that I'm a cheapskate; after I bought my first external enclosure (from Newegg), I used it to rescue data from HDDs owned by clients. After a while, I got tired of swapping HDDs, so I bought a second enclosure (you know where), then a third, and so on. I use one or another frequently, and having extra units saves me a great deal of time. Once you buy one, you'll wonder why you waited so long to get it...
Of course, you can also install her HDD as a secondary drive in your system; if her HDD is a SATA device, it will run on a SATA channel. If it is an IDE device, you'll need to install it alone on the Secondary IDE channel, or attach it as a Slave to another IDE device, or set it as Master to some other IDE component. No matter how you look at it, using this method can become very complicated, ESPECIALLY if your system fails to detect her HDD, which is why I recommend using an external enclosure to rescue her data.
There are also other adapters available, but in my opinion, they can confuse people who aren't closet hardware geeks, so I think it would be best to work with an external enclosure. You'll need to buy one designed for a SATA drive, or one designed to accept both SATA and IDE drives, and be sure that it is for a 3.5" drive, NOT a 2.5" laptop HDD.
Good luck with this; let us know what you decide to do, or if you have any more questions.