Right, so long as you have OSX 10.2 or better (and you have!), the best thing you can do is follow the instructions found here:
http://www.macdevcenter.com/pub/a/ma...pc.html?page=1
In essence, you have three options, Websharing, FTP or SMB. SMB allows the Mac and PC to carry on like they are both on a small network, but to get stuff from one computer to the other you need to have a folder on the PC designated as a shared folder and use it as a staging point between the two. You also have to log on to the PC from the Mac. See the link for all the details ...
EDIT
Having said all that, from your original post it looks like you're actually having trouble with the network connectivity of the PC, which is something I can't help you with sadly. There are plenty of wise PC sages around here who can help with network troubleshooting however, so sit tight ...