Using ISBoxer/IS is perfectly fine with Wow. As with anything if you stay within the known rules and conditions, Blizzard should leave well enough alone. However always keep in mind that Blizzard can throw the ban stick around at will.

Blizzard is well aware of the ISBoxer developer and what he is doing and so far so good. We will probably never get a "gold seal of approval" from Blizzard on ANY multi-boxing app.

1 click, 1 action, no delays. Keep within that and you should be okay.

I use ISBoxer/IS on Windows 7 64bit with no issues. Just make sure you run both as admin level.