"Computers need clean electricity" is happily a myth.  They are much more tolerant of voltage and frequency fluctuations than some appliances, like tube-based televisions.   A popular computer magazine did a test of computer power supplies in the early 90's, taking them to low voltage, high voltage, wild frequencies, voltage surges/sags, and most of them still supplied steady outputs.  Modern computer power supplies are even more tolerant due to European regulations and since they can auto-accept 50 or 60 Hz, 120 or 220 volt inputs (with actual minimum and maximums much lower and higher than their name plate ratings).  In fact many of them will also accept DC inputs at similar voltages.  Lots of other consumer electronics have the same power supplies in them like flat screen televisions, cable boxes, etc.

 

Neither can be used in any campground overnight, and even if you are camped where you can use one, if you are near others in a campground or someplace like a Wal-Mart parking lot, you will make enemies running the old style for more than a few minutes.  For something like running A/C overnight at Wal-Mart (we prefer truck stops) or for charging batteries in the middle of the day for a few hours, you'll want the new style.  It is of course much more expensive, but over time the lower fuel consumption can make it pay for itself.

 

The smaller you go with generators, the less fuel they'll burn, especially if you get an inverter-generator.  My Yamaha EF2400is burns 1.6 gallons in 8 hours while running the A/C.  It will run either my A/C or my microwave - in my opinion there's no reason to haul around a much heavier 3000 watt generator that can run both at the same time, plus carry and burn the extra fuel, when the microwave is only used a small percentage of the day.