Windows 2000 has a feature that allows you to share an internet connection. It works by acting as a dhcp server on the windows client. The feature i believe is called "Share Internet connection." If you search the windows help database, you will be able to get more in depth information about it. I do not know, however, if this will work with a Mac connected to it. My experience has only been to connect other window machines.
Give it a try though, and let me know how you make out.
To share files between your PC and Mac, use DAVE. It allows Macs and PC's to recognize each other on the network.
Peace.
Ver