I think the biggest thing to think about is are you willing to pay the fine and jail time? I know in america, it's some where around a quarter to a half million for every infraction (USD). That doesn't include jail time, and it's a federal offense.
We have all used some form of pirated software, and I like many others absolutly despise microsoft, but right now, the law is that it's illegal, and for no other reason, you should be respecting your government and her laws.
Besides, if you use pirated software, you will be caught, plain and simple.
Alternatively, I choose to use as much non-MS software as humanly possible while still maintaining useability. Thats OpenOffice.org, AVG, Mozilla, so on and so forth.
Also, if you are looking for an absolutly free OS, try Linux. Very much like microsoft, not as many viruses or spyware. Great for "developers", you can tweak the OS to your hearts desire. The OS could also stand for Open Source - that was a funny
. and best of all, it is legally free!!!