is it as easy as just forwarding another port other then 21 to my laptop and having them login to that port? and, will it need a different pasv port range than the desktop server?
For standard PORT, you need 20 and 21 on your router to be forwarded to 20/21 on your laptop. For PASV, you need 21 and some range that has to be specified in both your router NAT and on your ftp server. Sounds like you know that. Now because you're behind a router, the ftp server needs to know the external IP (in a PASV connection, your server tells the client where to come in).
Not all server software is equipped for PASV behind a firewall. Check that first. If it is supported and you're on a dynamic IP from your ISP, you can generally use a dns alias kind of service and then just specify your IP by name, allowing the server to do the look up so you don't have to change the IP in the server setup everytime your IP changes.
To answer your question, you can do it two ways.
1) set up the server the same way on both machines and use your router NAT forwarding to determine which machine gets the ports forwarded to it
2) set up the servers on different ports, each with their own set forwarded to the appropriate machine. So you might log into port 21 for the desktop and port 6445 for the laptop.
And if you want to support PORT as well, don't forget to forward port 20 (or port x-1, where x is the port used for connection).
make sense?