How to replace my iPhone glass cover?

I just dropped my iphone4. Should I use a replacement service to fix the glass or pony up big bucks to buy a replacement? Will I be able to upgrade if I use the replacement service?

I don't know, i do know changing the cover yourself is a long and tough process that one wrong move will make it worse then it is now. I would go talk to your local store or call Apple care if you have it