I'm trying to set up a simple ethernet connection between a mac and PC, but it keeps having limited connectivity, and being a PC uses I don't know how to set up the network on a mac. I had it working once but as soon as I turned to computers off it broke and won't work again...

I'm not sure of the direct answer, but something on the following sites may be of help to you. I hope that it is.

Mac Connect - networking Mac and PC

Networking with a Windows PC

Apple - Small Business - Mac & PC - Networking

MacDevCenter.com -- Connecting Mac OS X to Windows PCs

MacWindows Tutorials