http://www.microsoft.com/whdc/system/platf...PAE/PAEdrv.mspx (very technical) Actually, looks like xp cannot use more than 4gb physical ram. You'd probably have to upgrade to server 2003 or similar, where you can have something like 32GB.
NeorageX has no command-line parameter, it is its own front end. You can only use GameEx (or any other front end) with emulators that support starting an individual game from the command line, such as MAME.