Is there a safe alternative to electrical grounding for computers in Argentina?
I came across this APC product page for Microsol Isolator Modules, which purportedly provide "safe power in places with poor or nonexistent grounding."


This is probably an isolating transformer, which ensures no current can flow to ground, even if you touch the live wires. The only way to get shocked is to touch both the output live and neutral. Requires a rather bulky, heavy, expensive transformer, though.


  If I used a bootleg ground in combination with a GFCI outlet, would the GFCI kill the neutral end of the socket and prevent current from being pushed from neutral to "ground" to my equipment? 


The main issue with this, I believe, is that neutral and live may be swapped somewhere - this would make your chassis live. There may also be a slight difference in the neutral voltage, due to voltage drop. As such, it's preferable to leave the ground floating, and trust the RCD/GFCI to trip if something goes wrong.


  Ground is tied to neutral at the service entrance but nowhere in the walls. Is there some other kind of second circuit breaker or box I could install in my room with a computer and ups that would be more like what's at the service entrance and less like a bootleg ground?


It would be electrically the same as a bootleg ground, really. Unless you added another ground electrode.


  When testing outlets at home, I can see the voltage spiking to 1000 volts on my multimeter every few seconds, but only on some outlets (all are single-phase, 220v). What other kinds of voltage regulators will work without ground? Most of my electronics are dual voltage, so ideas including transformers that step down to 110-125v would be fine too.


The best place to put a surge protector is in your main switchboard, because it covers everything and has the best ground. You should be able to get surge protectors specifically intended for here.


  Can I hook a voltage regulator up to a GFCI outlet and then hook a UPS into the voltage regulator to deal with nuisance trips from the GFCI and avoid hard drive failure? Can I still get surge protection without ground?


I don't think the surge protectors are anywhere near as effective without a ground. You also need to make sure all the other cables going to your PC (especially coax internet) go through it.


  There's a grid of galvanized steel cables, spaced about one foot apart and set into the concrete walls outside which are there to hold up a grapevine. The cables are about the same gauge as a fence, maybe slighly thicker than the copper electrical wires in the wall. If I get good readings on the multimeter, can I use that as a ground? Will it electrocute the neighbor's cats who climb up on the vines or burn the grapevine? What would "good readings" (volts/ohms) be from the multimeter?


If they're connected to the reinforcing bars in the concrete, this could be a good ground. Remember to tie the neutral to your grounding rod - without this bond, it's almost useless.

There isn't an easy way to test that it's a good ground.