Ultra VNC in Windows XP SP2

> Hi,
> 
> I just got UltraVNC for Windows XP <\l > , and ran the VNC Server. And
> I tried connecting to my computer using VNC Viewer from another
> computer running XP, I tried putting in "myip:5800" and
> "hostname:5800", but both resulted in a "cannot connect" message. I
> tried it on several other computers with XP and it's the same problem.
> I even tried connecting it using my browser by typing in
> "http://ipaddress:5800" but that didnt work either.
> 
> I disabled my firewall. (Strangely, my windows XP firewall option is
> "greyed-out" and I can't enable it). 
> 
> Note: I already have qualified ports 5800 and 5900 in the Firewall
> 
> What am I doing wrong? By the way, if I can't just put in the
> numerical ip address <\l > , how do I find my exact host name to put
> into the VNC viewer?
> 
> Thanks,
>