we had one before we got more permanent air con (we have just moved into a new house and now are back to square one again)...

we had an old fashioned house, with windows that slide open vertically, but if your windows slide open horizontally, it will also work well with the air con vent that needs to slot in. if your windows wind outwards it is not going to be ideal having a portable air con vent attached to the window...

i just wanted to mention something i saw the other night at our local pub.... they had two of the more modern air conditioner units (i think they are called split systems?) mounted on INTERNAL WALLS, with a tube coming out of the unit and going up into the ceiling and probably outside somewhere... i have never seen this before, and have always been told that air conditioners must be mounted on an external wall, yet here before my very eyes are two air conditioners with these tubes taking the hot air outside.... definitely worth investigating!!

in my experience portable air cons are only good if you have the right window to get a good seal around the vent, and also if it is a small closable room (ie with a door, not open plan)...

in any case they are better than nothing, but i would be asking some air con installers about those tube thingie's that i saw.... they didn't look too bad at all.