Three months ago I posted some links to services which allowed you to test your website in Safari. Most people use Windows these days, and KHTML/Webkit is the only major browser not available on Windows.
Click the image for a full screenshot.
WebKit has since been ported to Windows and there is now a browser called Swift which implements it. It’s at version 0.1 alpha stage and the browser itself is pretty rough – it crashed on me several times, a lot of stuff doesn’t work, etc. Additionally, the mousewheel and right-click doesn’t work.
(Oh, install it for all users on the system, not "just me" or it won’t work)