Does anyone know a list of all registered companies around the world?

You wont be able to find that. Local company names dont have to be registered globally. But then it also doesnt matter if there is a conflict.

Try www.uspto.gov for trademarks. Most international/non-local companies trademark their names.

-Geoff

Most companies are not registered as ghowland has said. On the Gamasutra site you will find an article concerning starting your own development shop. It talks about company names, product names and just how the business, patent and trademark laws work. Information in this article will lead you to places that can help you determine if your name has been taken.

Click HEre

Hope this helps.
Kressilac

Thanx for the replies,
Ghowland: The site you pointed me to was the thing I was looking for.
Kressilac: I will look into the other site as well.