I'm a noob as well and I just bought a Venture cx two weeks ago and I love it. I don't know what is involved in creating your own maps, but for the money, I am hugely impressed by the maps I purchased as it even has new roads in my city that don't have houses on them yet. I live in Canada and I purchased the Metroguide Canada product.
I would recommend you get the Venture instead of the Legend if you want waypoint/map software as it is cheaper and the hardware is identical other than the colour and the included microSD (tiny) on the Legend. I used the money I saved and purchased a 1 GB memory card for less than the difference in price. All of Canada fits into under 400MB so I still have 600 MB to store other maps and track logs. On page 27 of the manual (you can download it from Garmin) it clearly states that in the TRACK setup, it is possible to configure the unit to record track logs to the microSD card and dump them to a computer as GPX files. You will still have a few bucks left over and that can go towards buying one of the Mapsource street or topo maps. All of these map products have the same waypoint management capabilities as the waypoint software that comes with the Legend, plus the actual maps so they are a decent deal. I use this software to import waypoints and view everything on the maps on my laptop. I also manage geocaching waypoints using GPS Swiss Army Knife ($20.00) which is capable of dumping waypoints to the unit, but not maps.
