The Data Encryption Toolkit for Mobile PCs has just been released by the SA-SC (Solutions Acelerators - Security & Compliance) team and I highly recommend pretty much any IT administrator that has a mobile workforce (and who doesn't these days?) to take a look and read it.  XP & Vista provide some great technology that you can use (for free!) to secure corporate sensitive data but there can be some caveats, this toolkit does a great job of explaining that and giving some great implementation details.  The two components now available for download are:

Executive Overview
The Executive Overview provides customers with a high-level overview of the Data Encryption Toolkit for Mobile PCs to help them understand the business and regulatory risks of losing data on mobile PCs, and how they can use the guidance in this Solution Accelerator to mitigate these risks.
Security Analysis
The Security Analysis discusses in depth a number of unique risks associated with data on mobile PCs, and analyzes how Microsoft's key encryption technologies, EFS and BitLocker, can help customers mitigate those risks. The Security Analysis now available on TechNet and the Microsoft Download Center.

The following will be released soon:

Planning and Implementation Guide

The Planning and Implementation Guide describes how to plan for, configure, deploy, and operate EFS and BitLocker in a customer’s organization. A Beta version of the Planning and Implementation Guide is currently available.

EFS Assistant

The EFS Assistant lets customers centrally control EFS settings on all their mobile PCs (and many desktop PCs, too). The EFS Assistant will help customers find all the files on their mobile PCs that need to be encrypted, regardless of where users save them. And the EFS Assistant operates transparently to end users, eliminating training issues or other impacts.  A Beta version of the EFS Assistant is currently available.