Assuming you have this three condition:
1) You are using two pc, one knoppix and one windows (running apache)
2) Both are in netwok
3) Both are connected to internet and assigned dynamic IP by your ISP
4) The windows pc has a static IP.

Two things you can do:
1) register to any free dynamic domain name provider. I would suggest :
http://www.dyndns.org/. You will get your own domain name and use that name, like you usually did with other homepage. Get free dydns updater so you can update you ip with your domain name everytime your IP changed.

2) You could either direct your browser to IP of your windows pc or to the Dynamic IP of your windows pc. If you are sharing connection, you can run on knoppix : ifconfig -a ; and look for inet addr: xx.xxx.xx.xx
and in windows : ipconfig. They should be the same.
If you're not sharing connection, just get the windows dynamic IP.

Assuming you only have one pc, which you share windows and knoppix, and knoppix is installed on hardisk. The easiest way to test your webpage is by copying those webpages from windows to your knoppix /var/www folder.
Then run /etc/init.d/apache start.
Then direct yout browser to your knoppix IP address.( offcourse after you set your knoppix with static IP). No need to be connected to net.

Assuming you only have one pc and you run knoppix from cd.....I can't help you. I don't know how to transfer file to /var/www folder virtually. Somebody please help him and me.