floating the DUT and isolation transformers

I'm looking to help protect against frying my DUTs, oscilloscopes, logic analyzers during testing. I've been thinking about purchasing an isolation transformers, and I've watched a couple video blog entries on the subject. [1] While I'm pretty careful what I'm probing, I don't want an inadvertent short of the test equipment ground to the positive supply rail off my DUT to blow stuff up. The strategy I intend on using is this: 1. Connect the primary side ground of the isolation transformer to ground with a normal(US) 3-prong plug. 2. Float the DUT by using a 3-prong to 2-prong adapter when plugging into the secondary side of the transformer. 3. Keep the o'scope or LA grounded with a normal 3-prong plug. My DUT for the most part is a commodore amiga that has an external 120v to +12v,-12v, and +5v power supply. I'm not intending on opening supplies, troubleshooting/repairing them or generally touching anything that has live mains power following through it. The signals I'm probing are generally ground-referenced single-ended signals. Does this approach sound reasonable? I'm looking for practical actionable advice. I'm looking at the BK1604A. [2] Thanks, Keith [1] http://www.toddfun.com/2011/04/30/isolation_transformers/ and http://www.youtube.com/watch?v=xaELqAo4kkQ (which is eevblog #279) [2] http://www.tequipment.net/BK1604A.html#