I like Perfect Resize - not just for resizing - but for options on wrapping. You can set the border width, and decide what kind of border you want. It also give you an option to create a separate layer for the border, or flatten.
If you are going to be enlarging your images to any degree - I would consider this tool over photoshop as it uses fractals which is a superior method of enlargement.
You can download a trial before you buy.