PC I OS = XP--connect---PC II OS = 2000
XP: a) right click:my computer>>>>property>>>>>>computer name>>>>>>Network ID>>> .... OK restart PC.
b)open my computer>>>> choose any harddrive you want share your file and right click it>>>>>>>share >>>>>>>network sharing..>>>>This PC ....gateway....>>>> you can choose to create a disk or finish it>>>>OK restart your PC.
2000: automatically find XP
c) you can copy files from both directions
through wireless networking. one computer can connect to the router directly. the other computer through wireless networking (need a wireless adapter). both can get on the internet independently. setup a workgroup using Windows. setup filesharing of the files you want to share. you can connect many computers this way. you can share printers; open file on one computer and save it on another computer; you can backup your files on another computer so you can reinstall your Windows on one computer. Wow, really convenient. my home is setup this way.
with wireless networking, share internet if the other computer directly connected to the internet is not on. you can share internet and files/data if both computers are on.
i think it is the best way and most practical and convenient way. the connection once setup, is permanent and can be used anyware in your house.