I started caching with a cobra 1000, still use it, and see myself using it for a long time. The main problem I had when starting out with the 1000 was that my laptop (in college its my only computer) didn't have a serial port. I got a USB to serial adapter, but the com ports would only work after some updates to the GPS unit itself. There is also an update that made my Cobra a lot more accurate. You can get these updates here.
http://www.cobra.com/index.cfm?fuseaction=...&page_id=89
Unfortunatly I dont know of any substitutes for the rand mcnally software, so you still have to make maps from that software.
Good luck!