Am I right in saying that you are starting the upgrade from Win98 to XP from
inside Win98? If so, IIRC, Win98 can't actually see or use all 2GB you have installed anyway, so the fact that 2GB is installed is not relevant.
This is really stretching my memory, but I suggest you run "msconfig" and un-check items in autoexec.bat, config.sys and win.ini (or edit those files manually,
keeping backups), so that fewer things load, after which you have to restart Win98. Target anything you recognise as "extras" - if you don't know what it is, leave it alone, or Windows might not start, and require Safe Mode (F5) at boot to fix.
Do not go deleting files like command.com - the process should not require you to do anything like that. command.com on Win98 is the program that
provides the command line, so deleting it from the command line is like sitting on a branch of a tree and sawing it off!