IPSec has traditionally been used to secure remote access connections. In the last few years this has been changing, as IPSec moves from the WAN into the LAN to secure internal network traffic against eavesdropping and modification. The whole thing is pretty complex to set up and manage, and though IPSec management tools were improved in Windows XP, they’re not really very intuitive to use. Things are going to be better in Windows Vista, at least to a degree.