In that case it's logically some other config problem. You should probably first uninstall then reboot, then do a clean reinstall, then reboot. See what sort of error messages you get (you might want to leave your folders in their original paths to begin with - in other words, go clear back to square one....)
Make sure after you reinstall that you can access the Xampp "choose your language" splash page in your browser of choice. If not, be sure you've used the "install as service" batch file included (assuming Win XP Pro here - if you are using some other flavor of Win32, I haven't a clue and can't help you much....) and then open Administrative Tools from Control Panel to verify that apache is started as a service (double-click on the apache service line to make sure that it's set to automatic start....)
Sometimes you have to shutdown/restart several times before Windows gets it right y'know, so try that trick too. Then open some browser BESIDES IE, and input "http://localhost/*path to ssi.html" (can't get more specific than that - I don't have that particular file in my installation); I NEVER test stuff like this in IE because it's just so totally broken.... if you don't have another browser, go download Firefox 1.0 Preview Release at www.mozilla.org..
Then of course, if you're still stuck, it's time to do some searching and see what httpd.conf lines you might need to tweak. Repost here if you need to do some more of that, and I'll try to give you a list of links to tweaks I tried (none of which it turned out were necessary.... oh well....)