Trouble with Networking (Cant find any other computers)

Hi
I have an issue with my Networking i have a Macbook running OSX 10.5 and most of the time my network doesn't contain any computers that should be on on my network. On the rare occasion they do sometimes show up :S. I have tried connecting manually via the finder>Go but it doesn't work. I also checked my "Shared" options and there is nothing wrong there either.
Could someone please help me solve this problem.

Thank you!

More often than not, this is usually because sharing isn't enabled on the other machines and/or, they're running a firewall that keeps them from broadcasting their availability of services.

I checked those possibilities and the computers are enabled for sharing and it is not a firewall issue because they are still able to connect to each other however not to mine :/

Check the workgroup setting to see what it's named on the other machines (I'm guessing they're Windows). Then set your Mac to use the same in System Preferences => Network => choose the appropriate connection in the left pane => Click Advanced => WINS tab => Workgroup field.

Their also Macs