I'm sorry, but I don't know what you mean by "segment" nor how to find the answer to your question.
Are their IP addresses on the same LAN segment?
Does the router keep the wireless and wired network segments separated thus preventing this?
We can (usually) tell by the IP configuration.
from a command prompt in Windows, and
from a terminal (konsole, xterm or other) in PCLOS.
Also, how is you network setup?
For instance, mine is like this:
Internet <-- modem <--> router <--> wired <-- wireless
(Actually, not the most secure, because my wireless has access to my wired (need to access files that way), but my wired doesn't (by default) have access to my wireless)
BTW, if you do not have some kind of hardware router in front of your Internet (resulting in a public IP on one or more of your PCs, etc), you may want to hold off on posting this information until we can clarify only the relevant portions...