Windows 32-bit /PAE Boot Switch?body{font-family: Geneva,Arial,Helvetica,sans-serif;font-size:9pt;background-color: #ffffff;color: black;}p{margin:0px}
Most systems runnning Windows XP when using the /3GB switch, also require the /userva=2900 switch.
The OS is just over 1GB, so you have to allocate enought space to it before extending the user space allocation.
Ben