Today I’ve discovered a great testing service : browserstack.
You can test using a REAL OS your web pages, and see it using : Windows XP, 7, 8, OSX Snow Leopard, LION … and also IOS/ANDROID using the emulators.
Available browsers on Windows 7:
Wait! Internal URL?
Yes you can also test your local web application using a little java proxy program:
And after the connection:
And here is the test VM (the screenshot refers to a local web page on different port):
The only word to describe this service is : MAGIC!!!!!
Note: this is a real OS (with limited features for security reasons), here is the demonstration: