My friend do not be afraid to take your bike into a shop. They will at the very least be able to tell you what size hub you would need. You won't need to replace your front wheel, but you can if you want (i.e. an upgrade either for aesthetic or performance reasons or both for people that find speed sexy). Oh and they're not referred to as 700cc hubs, but what you are looking for is a "road" hub. They are mostly found attached to 700cc wheels so i can see the confusion there. Anyhow if you would like to know a lot more interesting stuff about wheels you should check this out. Sheldon Brown will always be the man.