Help me upgrade

So, I have a web host, Hostgator, that I run this site on. It’s got a great program named cpanel that manages installation of things like wordpress – which I’m using here.

I’m a couple minor revisions behind, and I’d like to keep up, but the fantastico installer tells me to

Upgrade only if
– no files, languages, themes have been modified
– you haven’t added mods to this installation of WordPress

What is this all about? I can’t automatically upgrade if I’ve created a theme or added a mod? Who runs a blog without a theme or a blog. How useless! Grrrr.