Hi,
Samba is what you will most likely want to share files, should allready be on your system but just needs configured.
http://us4.samba.org/samba/
This is from my experience, but when I was running a 2.4 kernel then yeh, NTFS write was at the best shaky, but on a 2.6 kernel I have had no issues writing to an NTFS partition, and I weekly backup > 225G.
Hope that helps a little.