how to access my other network connection?

I have a cable modem, running win2k and I access a linux box connected thru my router (home network) - If I VPN into work, then I can no longer access the linux box with 192.168.x.x... and ipconfig tells me I have 2 network connections... how can I telnet to my local linux box on my router but still access my company network? Is there a command to switch between the 2 "virtual" ethernet adaptors?

Also, I note that if I remove my router from between the cable modem & computer, my network mask is 255.255.252.0 - what is the max number of users I can configure with that? My router apparently reduces the number of users to 253 because thru the router, the network mask is 255.255.255.0 - is that accurate?

Thanks!