The right places to store things:
1. Your files in your account (your 'My Documents'/'My Pictures' etc)
2. Her files in her account (her 'My Documents')
3. Common files in Public Documents/Public Pictures
In Libraries you'll see both Public folders and your own folders, so everything is easy to reach.
My wife and I always shared my laptop. We never created seperate login accounts to separate our files. Now with windows 8 we created two accounts due to all the syncing with apps. But in the windows explorer when she goes to My Music/Pictures/Videos/Documents nothing is in the folders. But under my login its all there. Is there a way she can get all my files under her login account? Oh and both accounts have administrative rights.