I think that they are not "snooping" into your system but into the traffic to and from it. That is if they are bothered with any of your traffic. Therefore it could be the security of the servers that you interact with rather than your own system that you could possibly be worried about. So it doesn't really matter whether you run Windows or whatever. Unix used to be fairly secure.
Woolwell, and of course the good old UK, married to the USA. It's really laughable as to the data they collected will be overwhelmed by what they can find. Simply put the US have put strained relationships with a lot of countries over this. With the exception of the UK which is hand in glove, no doubt. We're the stepping zone to Europe for their U.Spyware. Airways. ACME. firm.
"Simply put the US have put strained relationships with a lot of countries over this."
That may be the case, but to understand America's actions you need to understand what a massive shock to the nation 9/11 was. That shock is still reverberating in the national psyche, and it has coloured the country's whole approach to national security.
In Europe we've become accustomed to all kinds of terrorist groups detonating bombs - it has been happening for a very long time. We tend to take a pragmatic approach to such things - we know that you can never eliminate terrorist actions, no matter how alert you might be. America doesn't have our experience, but it does have a history of knowing that it is the richest and most powerful nation on the planet. Americans believed their country was unassailable, and to have that illusion shattered in such a fashion has left them understandably jumpy.