To test bits of code etc I run IIS so I have an Intranet http://my_computer_name.

However I don't want anyone to be able to visit this I want it to be only accessable to me on my machine, ie if someone puts my IP address I don't want them to see my Intranet.

I have seen the settings in the Administritive Tools area of the Control Pannel what is it best to set these to to prevent access.

There are three areas where settings can be made

Web sites
FTP settings
Default SMTP server

Or should if the XP firewall (SP2) is on should that be enough to prevent access to it.

If you activate the firewall and block port 80 it will not allow access to your computer using http.

Regards

I assume that Port 80 should be blocked by default to incomming traffic.

Port 80 is not listed in the list of allowed and blocked programmes and the only Port option is add port (with a note when you click it about the dangers of opening ports)

Just ask a friend to test if they can access your computer using a web browser, if he canot then the firewall is working.