Posted 14 July 2011 - 08:27 AM
Rereading your post, it looks like security is the primary concern?
Whether the IP is assigned by DHCP or is fixed shouldn't be too much of a security issue for the computer itself, but it may be for the network in general. Personally I only like to have the router / firewall allow a couple DHCP connections, and then block everything else that I haven't already assigned a fixed IP to. For a home network, this really shouldn't be much of a security concern.
As for the unsecured network, if you are running a wi-fi network without encryption, you really need to change that ASAP. It's easy to do. You should be able to figure out how to do so from your router's software (again assuming a home network). When it gives you a list of options, don't pick WEP as this is only mildly more secured than no encryption. WEP is mostly just a "please do not hack" sign. Choose a type of WPA as it is much more secure.
I agree with Dirtdog that we need more information...
I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it ot pass over me and through me. And when it has gone past, I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.