[jmaskell]

There are two main advantages to buying an off the shelf company:

1. Having a company that appears to have been around for longer than it actually has (although it's pretty easy to find out it's history - e.g. when directors changed).

2. Getting the company name that you want. There are a number of people that form companies and register them as dormant just to squat on the name - just like people do with domain names.

Edit: forgot to add:

I'd recommend registering a fresh company. It's quick and easy. Buying a company, changing directors, making sure there's no awful legal history with it etc probably isn't worth the extra cost or effort. It's nice to have a clean slate to start with.