Computer help, Vista hell, driving me mad. What can I do?!?

Look up the RAM type from the supplier website and buy enough to double the existing memory - Vista needs loads compared to XP and most laptops never come with enough memory even for brand new models. If, as you say you're not very computer literate, installing something like linux will just cause further confusion, and you need to know what you're doing with backups if you're going to reinstall XP. Also, it may be that the camera drivers are only for XP - see if the manufacturer has updated drivers for your camera?