The software is at www.realvnc.com
You will want the Enterprise edition. Under VNC Downloads, you can select the edition you want. You can install and test it free for 30 days.
Setup is pretty simple after you install.
You just tell it want kind of authenticaion you want on the server side (in the options)
Your client connets via a client on the PC.
Supports Encryption.
I also enable locking the keyboard during a disconnect.
I also remove wallpapers and stuff for faster preformance.
I disable the web portion of it (also in the options).
After 30 days, you'll need to either purchase or remove.
Edited:
If you have 10 guests, you'll need 10 licensed copies of VNC on each guest (I'm sure you realize that, but thought I'd better put it out there).
Hope this helps.
If you need more guidance, come back and ask and I'll try to help you out.