I have successfully been able to use a tool for RDP and VNC to connect to local machines, and RDP to remote machines with an outward-looking IP using the three Tools below:

I'm using the free program called ChrisControl, search for it on Google.

Name: RDP Local
Command: C:\ChrisControl2b2.exe /h:[Device.Name] /r /u:[Device.UserName] /p:[Device.Password] /go

Name: VNC Local
Command: C:\ChrisControl2b2.exe /h:[Device.Name] /v /rvncf /noask /remvnc /go
Description: This automatically installs a VNC server, connects and upon disconnect it uninstalls that VNC server on that computer

Name: RDP Remote
Command: C:\ChrisControl2b2.exe /h:[Device.FirstAddress]:3390 /r /u:[Device.UserName] /p:[Device.Password] /go

My question is this -- Is there a way to RDP or VNC in to remote computers that are on a remote network?

I have an echoserver running, but that requires software to be installed on the machine I'm trying to connect to.

What OS are you useing. I cant get chriscontrol to work with Windows 7

To connect to the remote computers you will either need to give them real internet addresses or nat them to a real address and then allow traffic through the firewall (from your address) or you will have to create a vpn tunnel and a set of routes that will route traffic to the remote network through the tunnel on both sides of the tunnel.