Cranks,

If you're looking to create a map on the web, save it, and download to your device. Just look at two:

For Using the Navigation features of your 605, use bikehike.co.uk
It's not sexy, but it will save your routes, and draw you the profile as you draw your route.
Also, download the route to your 605 as a gpxx file for navigation. It gives you great turn by turn.

If you want to use the course mode, and add/edit your own course points, go to www.bikeroutetoaster.com. This also gives you a rough profile, and the site lets you edit the names and values of the course points as a "cue sheet". Download the file as a .tcx and you'll get all the features of the course (virtual partner, distance to next, etc).

For tracking your progress, Garmin Connect is a decent start. Nothing to install on your computer, and it gives you enough of what you need. Sporttracks is a great desktop application, but I switch computers a lot, so it's tough for me to keep that up to date. Also Garmin Connect added a manual entry, which is great for when you don't ride with the GPS.