Question : Win 2003 or SBS R2

1. although Ive read, Im still completely failing to understand the differences between:

- eval copies, which work perfectly as far as I know as Im currently using one for a period of upto 180 days?

- R2, im still not getting the difference, or is it just a SALES PITCH thing for customers?

Answer : Win 2003 or SBS R2

Another major point is DFS which has improved replication.

I would suggest you review: http://technet.microsoft.com/en-us/library/cc773240.aspx

Not sure why you said "Win 2003 or SBS R2" - these are very different.  Win 2003 - as in Windows 2003 is a server product.  JUST Windows Server.  SBS is Small Business Server 2003 R2 - which includes R2 features of Windows 2003, but also includes Microsoft Exchange, WSUS 3.0, Remote Web Workplace, and other features, many of which are not included with 2003.  Further SBS has some restrictions that 2003 does not have - you may only have one SBS server in a domain for example.