I have a 95% OS X server shop..and just a handful of Windows servers I occasionally have to mess with... I need to resize some disks on a Windows 2003 box, and am looking for the equivalent of OS X's Disk Utility, if there is such a thing built into Windows 2003 server...Disk Management is not a part of Windows 2003 I am assuming?
"Disk Management" in the Computer Management console is the GUI version of diskpart's functionality - you can resize partitions and perform similar functions from there.
As a gotcha, Windows 2003 can't resize the System partition, you'll need something else for that (or to boot another install of Windows).
You can try GParted:
There is a nice PowerShell-Gui (also for Win-PE) out there:
For more advanced partition resizing i recommend using free third party tools either for installation on windows or live-system booting into a cd/dvd/usb (list only for example not for complete reference!)