Window A/C conditioners (at least in the US) are pretty crappy. They're really only meant to cool a single room, they can't really do that, they're generally noisy, and the weatherstripping around them lasts about a month before it starts breaking down, and you're left with big gaps all around that'll easily allow plenty of bugs and outside air back in.
If my central A/C conked out tomorrow and I didn't have the money to fix it, maybe I'd put one in the bedroom, but it would be with the understanding that it was temporary until I could get the main unit fixed.
We have ours serviced twice a year, on a maintenance plan, and it's been worth every penny. Both neighbors either side of me, same builder, same style house, and same HVAC system, didn't maintain theirs and both have had to have theirs replaced - mine is 14 years old and still going strong. The only issue will be if it develops a leak, because the refrigerant it used is no longer available, so I won't be able to have it recharged.
Speaking of server rooms - when I worked in a more traditional IT shop, that's always where I had my desk set up. Those were always about 65F and on top of that, no one would come in there unless they had to because of the temp.
