Windows 7: remote desktop for an idiot

I want to access a PC at work that uses XP from my PC at home which uses Windows 7 pro.
I have enabled remote desktop on both machines and have tried connecting using the IP address of the works machine but it won't connect. I seems to want to in that it takes a minute or two trying.

The work machine in not on an intranet but it does have what they call a dirty broadband connection.

What i am trying to do is Access a program that controls all our plant at work, sometimes i am asked to either switch on or switch off a particular piece of plant at the weekends

Probably the best thing to do is go to your I.T. Department at work and ask for assistance. Any time you want to access a work computer from home their permission and help will be needed.
I have no idea how it would be done without internet access and I don't know what a dirty broadband is.
Your work place could also have a domain that the I.T. Department could help you with.

In order for that to work you need to open a port on your companies router/firewall to allow traffic on port 3389 to your work PC. Then from your hope computer you will have to use the public IP address of your company.

depending on how everything is setup on for the company you might not be able to browse the internet but as long as there router/firewall is connected to a wan they should be able to make it work.

Don't forget to contact you workplace Managers and I.T. Department before doing such things.

I knew there was something I forgot about.

Just a concern. We don't want to help people crack a workplace computer.