The Channel Insider has an article advocating Samba as an alternative to Windows Server 2003 when Microsoft ends its support of NT4. The article is a quick and easy read and excellent for anyone considering Samba. The author outlines several reasons why Samba should be considered. For example:

Samba is also fast. When I first tested Samba in 1999, it was already delivering files faster than NT. It's only gotten better since then.

For more, read the complete article here.