Safari has some browser market share and while it's tempting to just put it in the "ignore list", with IE 5 or old Netscape versions it's usually a good idea to test your websites in it too.

Testing on Safari is not easy when you're developing on a PC. You can run MacOS X with Pear, but this is slow as hell. You can buy a Mac. That's expensive unless you do not plan to switch to it. You can bug your friends with a Mac or you can use one of the online services that take screenshots of your website in various browsers and platforms.

Since the rendering engine, WebKit, is based on KHTML, some people use
Konqueror to test their websites. This works, but not fully since Apple modified KHTML so there are differences. And unless you want to try to install Konqueror on Windows using Cygwin, this is not an option.