Connecting problem

I've had this computer working perfectly hosting a website before, but i packed the cpu away for awhile, and now i'm trying to get it working again.

I can use the computer and type in localhost and it will take me to my website. I can type in the IP address that is within the control panel and it will also take me to the website, but if I try to connet to it using another computer not on my network, i get the error page. If I try to type in the ip address assigned to me by my ISP, i get a error page, no matter what cpu I use. I know if i can connect to the IP address given to my cpu by my ISP, then it would probly work on any cpu. Does anyone have an idea what i'm doing wrong or how to fix the problem. I'm thinking it has to do with some setting. IIS is installed, like i said, it used to work, but now i don't know whats diffrent. Any help would be greatly appreciated. I've disabled the firewall, and it still doesn't work.
Is there a tool that can help?
Using:
Windows XP Pro
IIS V5.1
PHP
MySQL

begging, please please help. tired of working late at night on this, and its probably something easy

Have you opened the http port through your router (if you have one)? Does your ISP block http?

My ISP is SBC, and has a firewall, but i set it to allow all applications, atleast till I can get the problem fixed. I've also disabled the windows firewall.

i hope that answers both questions.

But does SBC block http traffic? Many broadband providers prevent use of a webserver on their line.

Thanks in advance for everyones help. I don't think SBC blocks it, because I had it working about 7 months ago on thier network, but i will try to call and find out.

any other suggestions please?

This is not an IIS problem since the webserver works fine locally. Something in your network is the problem. You might try rephrasing your question and post in the networking forum.

You can use tools like telnet from a remote computer to try to identify if port 80 is open to the web server. Your dns may be incorrect. Likeliest to me is http is blocked by either your isp or your router/firewall.