syncing PSE6 catalog

I have a desktop pc running XP and a laptop running Vista with PSE6 installed on
both. All my photos are stored on an external drive connected to the desktop and
I use it most of the time for my editing. However sometimes I can't be at the
desk and need to use the laptop. Is it possible to access the catalog on the
desktop with the laptop and keep them both synced? My harddrive space on the
laptop is quite limited so the less I actually have to have on there the better.
If this is possible could I get step by step instructions to set this up? I do
have a network connection to the desktop.
Thanks for any help.