can vpns or rdc be comprised by a ireless hacker?

[Nightcheck]

We use SBS 2003 and have 3 remote users, 2 use VPN's and one uses Remote Desktop - all three have Server access.

Is there anyway that a hacker using a wireless device intercept
these VPN or RDC connections and obtain access to a workstation or Server.

Is there anyway at all that any wireless device can in any way hack into our Server/workstations.

I also recently heard - that it is possible, though not likely, that by dialing into our fax number a sophisticated hacker can gain access to our server also. I remember hearing about this a long long time ago, and assumed that security breach was rectified - bus is it ?

Thanks for any info you can provide...

NC