Great point, I really like when you said: "It's also important to make sure that your backed up data is located somewhere other than where your primary data is" That's a very important aspect of online storage.
I recommend also checking into services that offer backup for both Windows and Mac operating systems. SugarSync is a good example of this. To learn more about it, I recommend reading this comparison on Livedrive vs. MyPC Backup vs. SugarSync, it's very helpful in differentiating these 3 services.