Purchasing a Scan Tool

I've been reading this forum for several months now - it seems if you want to diagnose anything these days you need a scan tool. Does anyone have any thoughts on which one or type to buy for a home garage?

I've seen the hand held units at Sears or Walmart for $100-150 bucks, are those any good? I understand "Data Logging" is key - what is a good model that has that capability?

Also have an old laptop around the house, are any of those software programs and adapter sets worth the money? Any advice on those?

I use Autoenginuity - http://autoenginuity.com/

I also have the "Enhance Ford Option" -> http://autoenginuity.com/products-software.html#EI01 - which gives you this list -> http://autoenginuity.com/Ford-All-Systems-List.html

You can actually run all the same tests emissions and dealers can.

You can also datalog