I'm no computer nerd. How difficult is it to change from Vista to Windows XP? I bought a notebook for my daughter which came with Vista and we're having nothing but problems.

You must have the cheapo Vista Basic. I use one computer on Vista Home Edition Premium and one on Pro, no problem, much less than XP even with the latest SP.

Two options: upgrade to Premium or Pro or formate your disk, buy a genuine XP and install.
but beware, XP support and upgrade will be totally ended very soon and it still has security issues.
I am very satisfied with Vista after the July security update.
I am tinkering with Linux on an old computer I upgraded to have a backup.
You could download Linux free of charge, that's the third option.