Apache Confusion

In an attempt to learn tp change from HTML-based web pages to php/databased websites, I decided to install Apache 2.0.48 in order to finally have my own hosting, and so i could test my new php skills without having to upload to my hoster all the time.

I got it installed cleanly and running, etc. Before I installed Mysql and PHP I decided to test it. It all checks out good, the monitor looks happy. I got an old client's website in the root folder, and when I type URL or URL(which is the IP for your localhost), I can see the page. However, I cannot seem to set it up so other people can see it. I am behind a cable modem router (an SMC Barricade). I turned off its hacker prevention setting, and even got out form behind plugged right into my cable modem. I triple-checked my IP, which should be URL (for those who want to slam me )but no one else can see it still. I looked all through the HTTPD.CONF file, and nothing I can find will help me. Does anyone have a clue how to make it work?

Also, I'm running off Windows XP Pro. I know this is not the best choice for Apache, but with such a recent verison like 2.0.48 it should work just fine. Does anyone have any idea? Part of my job depends on this!!!!!

Thanks,
Taz