The mem command still works in XP. I have noticed that some of Dell's bios's don't support EMS correctly while others do. I have an Optiplex 745 at work. If I use the original bios, I get EMS. If I update my bios, I lose EMS. I've tried tweaking config.sys and autoexec.bat (himem.sys) with no luck getting EMS unless I revert to my original bios. I get the same behavior with other Dell models.