Hi Stuart
not sure what's happened here now....I get a 404 error - which means "File Not Found". I took off the "mambo" bit of the URL and got a file listing (never a good thing) and Mambo wasn't one of the directories I could see.
Is the path correct? Is mambo in a directory called "mambo".
I can find an installation in a directory called "testing" (which is why you shouldn't allow ppl to browse the directories - they snoop around

)
The install in "testing" is showing a path to "10.1.1.5" (if you view the source of your page you'll see what I mean).
If you've created the site on your local machine and have transferred it to the remote server, then maybe (and I'm talking through my hat here, cause I've never tried it) you've not copied all the required files up.
Can you run the administrator and select another template (say, SolarFlare) and display the styles etc properly?
Don't give up - it'll be worth it in the end!
Sue