Can someone explain these remote control apps that are on a PC in our office?

was looking at a machine provided by a vendor of ours to handle dictation services to us.  It had both Real VNC and Remote admin (radmin.com), which are both remote control apps like PC Anywhere, right?  Any idea why they would have both?  Their tech is not all that friendly / doesn't like dealing with people much and I'd like to understand this.
 
I figured out how to look at the admin panel of the router and saw these ports are forwarded:
 
App         Ports             Send to
VNC    5800-5900      .200
R Desktop    3389      .200        
R admin        4899      .200
IRC                   194      .254
IRC           6665-6669    .254  
????       137-139          .254
 
It also filters  ports 6665-6669, 7000-7100 and 194.
 
.200 is their machine and is the DMZ
 
They have a dynamic DNS service running on our DSL service

And if you don't mind me asking - on an XP machine, why not just use XP's Remote Desktop?  May not be as good an app?
 
Thanks!  I know just enough to be dangerous!