I should qualify the Mac thing:

As of a year ago, the word on desktop-ish Macs was: avoid modified sine wave inverters, period.

I have no solid info as to whether this applies to laptop-ish Macs. Ask the question of a suitable guru: "if I do this, will it cook my loved one / void my warranty?"

FWIW, I have never used a cheapo inverter on a desktop wintel box (yeah, chicken) but I have logged many hours on wintel laptops powered by uber-cheapo modified sine wave inverters. Not so much as a hiccup on three different machines. So it all lies in the design of the power supply.