I haven't used DeWalt or Rigid, but the Free battery replacement that is being offered sounds good.
From the Home Depot web-site......
Limited Lifetime Service Agreement for RIDGID® Hand Held Power Tools, Stationary Power Tools and Pneumatic Tools
In addition to the 3-Year Limited Service Warranty currently included with RIDGID Brand Hand Held Power Tools, Stationary Power Tools, and Pneumatic Tools, purchasers of these products may elect to receive a free Limited Lifetime Service Agreement. To accept this Limited Lifetime Service Agreement, you must register your product and submit proof of purchase as described below. The Limited Lifetime Service Agreement provides the original owner of qualifying RIDGID Brand tools a lifetime of free replacement batteries, free service and free replacement parts subject to the limitations set forth below.
The Limited Lifetime Service Agreement is available free of charge, for a limited time commencing April 15, 2005, on all RIDGID Brand hand held power tools, stationary power tools and pneumatic tools, subject to the terms and conditions stated below. Customers have 90 days from date of purchase to register tools for the Limited Lifetime Service Agreement.