Slow performance copying files to new Windows SBS 2003 Server

We've got a development environment with several servers -

NT4 SP6
Novell Netware
Windows 2000 SP4
Windows SBS 2003

The Windows SBS 2003 server is new, and we've noticed slow performance when copying files back and forth to that server from our workstations.  The workstation I've been testing from is a Win2K Pro SP4 workstation, so I shouldn't be seeing downlevel types of issues.  Here's my testing results.  I used a 920k Adobe Acrobat file.

Copying to and from NT4 server - almost instant (never saw "copying" window).
Copying to and from Novell server - almost instant (never saw "copying" window).
Copying to and from Windows 2000 server - ~3 seconds to copy
Copying to and from Windows SBS 2003 server - ~3 seconds to copy

Any ideas?  The new SBS 2003 server is a brand new Compaq 3 GHz machine with > 1 GB RAM, RAID 5 on 10krpm drives.  I wouldn't expect it to be this slow.