You are confusing a couple different issues. Let me try to clear this up:
1. The latest version of Google Maps Mobile can use cell-tower triangulation to estimate your location. This works for most carriers and phones (including your Sprint 8703e). Download from htp://www.google.com/gmm (if you have an older version uninstall it first)
2. Google Maps Mobile also supports GPS on some phones, but NOT with the Sprint 8703e internal GPS receiver yet.
3. There are several apps that DO work with the internal GPS. Search the GPS forum on this site (GPS & Mapping - BlackBerryForums.com : Your Number One BlackBerry Community
) for 8703e. I personally use both BlackBerry Maps (free) and MapQuest Navigator (recently went to a monthly subscription fee, but the free version is still available, read New Mapquest Navigator for $4.99/month