No individual has ever been prosecuted for using a cracked version of Windows, only businesses or people who try and sell illegal copies.
Not saying it's the best idea, just saying that instability/updates are the main problem, you won't get sent to prison or fined.
I've never paid for Windows.
Not entirely true. Although they are not aggressive about this and see it more as a conversion tool, I (partially) agree. However, you will be flagged by (at least) your ISP. In case you decide to get something from a company that is fighting piracy then it will be easier to find and prosecute you. I have both, pirated and original Windows. If one can attain it at a good price then there's no need to pirate (sometimes the offers are quite great).
