The following information was gathered from this thread: Cannot enable EMS under Win2K...

Problem: No EMS memory available.

OS affected:
DOS
Windows 9x
Windows NT4
Windows 2000
Windows XP
Windows 2003

Motherboards with EMS issues and fix:
Intel 845E
Abit KX-333R - Disable HPT372A and USB in BIOS.
ASUS A7N8X Deluxe
Shuttle FN41 - Disable onboard Nvidia ethernet.
Gigabyte GA-81K1100 - Disable onboard USB

Motherboards with good EMS:
ABIT KT7A
ABIT KR7A
ECS K7S5A Pro

Explanation:

Problem happens when hardware devices use memory addresses commonly used for EMS. Dos/Windows 9x can use the available memory addresses through EMM386 but Windows NT based operating systems will not use those available addresses....even if you specify them in CONFIG.NT.

Solution:

Disable devices in BIOS:

RAID Controllers (Highpoint)
Disable onboard USB.
Disable onboard ethernet.
Updgrade/downgrate bios.

Tools to try:
MS Diagnostics v3.01: ftp://ftp.sac.sk/pub/sac/utildiag/msd301.zip
Norton Sysinfo
QEMM MFT
WPCREDIT
Award Bios Editor: http://awdbedit.sourceforge.net/
MI: http://www.uwe-sieber.de/files/mi_e.zip
TweakBios: http://www.miro.pair.com/tweakbios/

Things to look into/writeup:
Disable shadowing in BIOS. (Possibly not helpful since they cache to L2)
Modifying BIOS to move embedded devices usage of certain addresses?
Size of BIOS, means less available?
Check memory using MSD
Disable UMB's in CONFIG.NT. Doings so leaves all upper memory to EMS page frames.
AGP eating up memory space.