Security in being Dom3 host

[NTJedi]

JaydedOne said:
So, I'm going to be hosting a dom3 multiplayer game. This means leaving a laptop on 24/7 with a persistent internet connection, something I generally don't do. I'm debating whether I want to do this with my regular machine, something that occasionally has work material on it which is of a highly sensitive nature, or with my spare laptop. My question then is this:

a) What sort of security risk am I at in so doing?
b) What measures can I take to allow for Dom3 hosting while preserving maximum security otherwise?

Depends on your operating system, but precautions can be taken to make your important stuff more safe.