Windows XP Pro W2K sharring a folder

I have one pc running W2K and one running XP Pro on a p2p network. I want to share a folder on the xp pro machine and give access to the W2K machine only. I have tried it on two xp pro machines in my office and can not get it to work. when I share the c:\ drive and let everyone have access it works. when i try to set permissions it does not. When I try to access folders on the c:\ it will not let me gain access even though it lets me access c:\. I am going to be doing this in the morning on the WXP Pro and W2K. The WinXP Pro was upgraded from home last week.