CrashSW

We have a pc at our office that we need to be able to connect to from home
and see the screen, be able to control the machine and most importantly hear
sounds. I have tried several 3rd party software programs for this but none
support sound. I have several questions:

1 What is the difference between Remote Assistance and Remote Desktop?
2 Does either support sound?
3 When I try to connect to the server from my home network or from the
server to my home network I get an error saying that the host name could not
be resolved. I suspect this has something to do with public/private IP
addresses and port forwarding on my router but have not been able to work
around it. I can take my laptop off my home network, use a modem to dial the
internet and control my PC at home and vice versa. I can also do the same
through the network, but when I try to connect between home and office I
always get the same error.

Desktop at office and Laptop are running XP Home, Dektop at home is running
Vista but was running XP MCE with the same issue. Netgear router at home and
Linksys router at office.

I suspect the problem is at home because I have a friend who could connect
to other peoples computers but not mine at home. Any help is appreciated