XP offers a the ability to use files on another machine even when that machine is turned off called "Offline Files".
- When both machines are on and connected the files
are always kept in sync.
- When one machine has been turned off,
and is then turned on (or disconnected and reconnected to your network) the files are
all re-synced automatically.
I don't know for sure, but I expect Vista has the same functionality.
To set it up,
(Assuming sharing is enabled on your machines)
Define one of the machines folders as "Shared" (Right click "Sharing") (Let us call this the local machine)
One the other machine (lets call this the remote machine), set those shared folders to be "Available off line"
- fROM the Remote Machine find the shared folder on the local machine
- right click
- select "Make available off line"
You should be all set. As you get familiar with syncing off line files, you will see some options as to when to sync. The default settings will sync as I have described.