I am running on Windows XP Pro with 2GB of RAM. I recently updated to Service Pack 3 (it was an auto-update). After updating, Vectorworks would not load.. it kept crashing about half-way through loading the software. Tonight, I finally gave up and rolled my computer back to Service Pack 2 and now Vectorworks is working again.
I recommend not updating to XP SP3 until there is a patch or the problem is resolved