nginx under Ubuntu 10.10 - 403,404 errors

[John Moore]

This is probably just something simple I've forgotten, but it's foxing me...

I've been using nginx for years in its various incarnations for years 
now, on Debian and Ubuntu. I've just installed Ubuntu 10.10, and 
installed nginx from the repository. I try out 'http://localhost/' and 
instead of the normal 'Welcome to nginx' message, I get 'Forbidden' (the 
403 error). So, I create a little test.html file in the nginx directory 
(/var/www/nginx-default) and try to access that. I get a 404 not found 
error. Nothing I've done so far has got me past these 403 and 404 
errors. Is this some permissions error, in which case what do I have to 
do? nginx is running as user 'www-data' (by default). Changing this to 
root didn't help.

Please, someone, point out to me what I might be doing wrong. Don't 
worry about embarrassing me with my stupidity...