Probably been answered 100 times before. I've never moved a domain name from one registrar to another, does doing that result in any downtime?
As long as you don't make any changes to your name servers you should not encounter any downtime. Just go to the target registrar and make the initiation of the transfer and things will go from there, it will be a matter of approving emails. Make sure that your domain(s) do not have the registrar lock prior to the transfer approval. if it is a newly transferred or registered domain name there is a waiting period before you can transfer them to a different registrar. WinkDomains.com is a reseller of Godaddy, and can offer you great service and assist you with the transfer, same domain interface as Godaddy. PM me if you are interested
DLGx, I think there are two questions: 1) Is your hosting company the same as your domain name company? 2) Are you changing your hosting at all when you move your domain? If you answered 'yes' to either of these, you may come into downtime issues, but if you answered 'no', then you should be fine.