I have a linksys router and 2 computers, one on wireless, the other connected directly to the router. I would like to connect to the wired machine from the wireless machine using Remote Desktop and access the file-system. How can I open up my routes to do this safely?
Unless you have a very unusual configuration, they're both "inside" your network, probably with IP addresses of 192.168.0.100 and 192.168.0.101. You shouldn't need to open any routes at all, just determine the IP of the wired machine and connect to it.
I know that windows xp home doesn't have an RDC server. If you're running xp pro or server 2003, you can access the settings in the control panel, system information (or whatever it's called), and then the remote tab, check to turn on RDC.
I don't have a Windows machine at home, so I may be off on the names but RDC won't work without that turned on. After that it's a simple matter of connecting with the RDC client on your laptop.
Another option might be to run a VNC server on your desktop and a vnc viewer on your laptop.
It all depends on what you're running.