You're going to need to resize it, something you can easily do with Paint. (I can't exactly lead you through it now, though, because I'm on Windows 7, which has a version of Paint that looks way different.)
Open it in Photoshop. I think it's called the Image menu or something, find "Scale image" or something like that. Set the unit to pixels and type 120 in whichever box has the larger number. Lemme know when you get that far.