Yes you can install Windows 2003 Server on a SuperMicro 370DLE, you have to do a couple of things though or your initial install will fail repeatedly! Go into the Bios disable the onboard LAN, SCSI, all ports - serial, LPT, and USB. There is something there that will stop the install at the 34 minute mark in the Windows 2003 Server installtion if you do not do this.
Use a PS2 Mouse and Keyboard for the install. Once you get through a login, on a restart you can enable the onboard LAN. Complete the installation of Windows 2003 Server and on a reboot, enable the USB.
Disabling the SCSI option will not effect your ability to boot from a SCSI controller, or install Windows 2003 Server on a SCSI controller/Raid Controller. The SCSI controllers Bios should have a boot option.
After you have completed the installation do everything you can to avoid installing service pack 1, and don't install service pack 2. In my case it caused this file acpitabl.dat not to load on startup and then it puts you in a perpetual loop, that you cannot get out of even trying to boot in safe mode. The work around for acpitabl.dat is to either install an inplace upgrade, http://support.microsoft.com/kb/816579, which does not register your programs in add/remove programs, or you will have to reinstall the OS. Which is what I had to do.