Should my laptop have a different external ip than my desktop, cause right now there the same. Also if im trying to set up an http server, could i get around this by just forwarding the HTTP's port to the laptop's internal ip?
WHen you say external IP, I guess you mean the WAN address, the one provided by your ISP? No, a router should handle the 'internal' lan addresses, and what is forwarded to what machine. You should set your router to forward port 80 to the server.
You can use any port you want, 80 is just the default... My brother had a server on port 80 at our house so I used port 30. It works just fine you just have to specify... Say your IP is 99.99.99.200, you'd type http://99.99.99.200:30 to access the server though port 30.
Oh yeah, and have fun as I think the ports go though like 65000 something ;P
If you have to use a different port, go with 81. Also, you can configure your DNS to automatically use 81. So people don't always have to type http://name.com:81.