Lori S, there is a Pfaff dealer in Buffalo:
http://www.totsewing.com/ Pfaff and Viking are 'sister' machines with many common (and some uncommon) features. The software will likely be the same, stabilizers and threads will be the same. You might contact the shop and see how they might receive her in classes with a Viking machine (in our community the Pfaff store is a little more receptive to Vikings than vice versa). As for the weight moving everything, which is an issue and I haven't been sewing for 70 years so I know I'm younger than your mother, get her a little wheeled cart (one that folds up takes up virtually no space) and a supply kit she can keep packed for class (if you're not familiar, the store can help with what she would need). Once she has some success, she'll probably be addicted like many of us! Embroidery Library has nice, inexpensive designs that can be downloaded to her machine so she can have some good results before she tackles digitizing. I wish both of you luck!