Code Scanner Options

[tynashracing]

I'd like to know my options for code scanners? I have 3 BMWs: e53, e46, e36
I enjoy playing detective work on my vehicles and fixing whenever I can. However, I'm not looking to spend thousands on a diagnostic system.

I know from reading here that the GT1 is the bomb and must be bmw specific...but I'm not sure what's really involved in getting it setup as well as the cost of the system. Does the program run on any windows based OS or does it require a particular package?
I have a couple of older laptops, one with windows XP and another with Vista. I could dedicate either of these.

Would a small handheld unit from Autozone or other parts places be OK? If so, is there a particular model that's more accurate for BMW's?

Just recently, I saw a thread that mentioned an app for android phones called Torque. Would this be as good as any of the hand held units that are not BMW specific? Obviously, this is a really low cost option and may be all I really need to get me going?!

I'd like to see the recommendations from all the veteran code chasers out there. When listing your recommendation(s), please also include:
package cost (program and any hardware required)
functionality (specific for bmw or generic)
ease of use (any weekend warrior can use or requires training/education)
source for purchasing

Thanks!