>With my grid class I want the user to be able to select the highlight color. I plan on implementing a right click menu to launch the color picker. To store this color I thought about using the registry so I could easily store colors for each grid if so desired and also so I don't have to depend on a table.
>Is this a solid design idea?

In multi-user enviroment it makes sense to keep it for each user separately, i.e. you have a table 'usersettings', or one setting for everyone in table 'systemsettings', and you provide interface to fill these entries.