[drivetowin]

Google does have a number of datacenters around the world - do a hunt on Google for Google Datacenters and you should find a list of them fairly easily - and yes results can and do vary from datacenter to datacenter - and Google decides which datacenter to serve results from pretty dynamically, so you could be sitting right next to someone else in your office and actually see different results in Google as one of you could be getting results form datacenter 'A' and the other one from datacenter 'B' (you can get the same effect sometimes by refreshing your browser too).

I wouldn't get too hung up on Google position, a) because it is visitors that are really important, you can be no1 for 100 different keywords/keyword phrases but if no one searches for them except you, your dog and your neighbour's dog then it's pretty irrelevant and b) if you are not on the first two pages of Google results for your keyphrase you may as well not be there, traffic drops off rapidly between the top and bottom of page one, drops off even further on page two (though there is some evidence to suggest that position 1 at the top of page two gets more traffic than the position at the bottom of page one) and by page three traffic is down to a trickle.

You do need to be careful with these automated keyword tools, a) because it may get your IP banned and b) because there is anecdotal evidence that too many automated queries can lead to your domain being penalised by Google.