In reply to idiotproof (Buxton MC):
You can indeed get Photoshop not a lot cheaper, but a lot lot lot cheaper if you get student software. However CS6 is due out next year, so I would hang on for that before getting an Adobe product. Not sure if a new Lightroom is due as well.
I have no idea what level of functionality your g/f needs. Picassa is free and might suit, Windows Live Photo Gallery will do basic editing, ie also free and is a pretty fair management tool.
However suggest she sets her camera to take both RAW and JPG, if it will, and she can go back to the RAW files later if she wants. Also make sure it is taking the JPGs at the highest quality and biggest resolution it can, and never, ever alter the original. Use 'Save As' to make sure you don't accidentally trash the original. Hard disk space will be cheap again, being mean about what size photos you take isn't the way to go about getting good quality prints.