The problem with upgrading to a newer operating system is the software was developed, tested on an earlier version of O/S. If you upgrade, then you need to do a thorough set of testing to ensure you're not going to have any issues. There's always a risk that something will break.
Eugene, Vista may work for you, at home, with the limited things you do, but this no gaurantee that it will work with whatever hardward cards, whatever software apps the LAS want to use, and note a failure rate of 1 in 1000 hours for you at home using your computer for 3 hours a day is probably acceptable, but for LAS using their systems 24 hours a day? A much lower failure rate needed and given the criticality of the service they provide to people, even lower still!
In safety critical apps(or investment banking!) , I wouldn't touch Microsoft with a barge pole, unless extensive thorough testing had been carried out and it had been proven to be acceptable.
I know of government organisations that hae moved away from Micrsoft operating systems a) to save money, b) to get something that's more reliable, so I'm surprised that the LAS is running Microsnot.
Running Microsnot for such a long term application as the LAS will use, must be a support nightmare, develop the app, install it, 5 years later the OS is no longer supported by Microsoft, what do you do then? rip it all out, re-develop and start all over again?
Each time you redevelop it you risk the introduction of new bugs, and you've only probably just ironed out the last lot with the previous release.