And people running Linux are even more likely to tell you that Linux is immeasurably better. Linux people are (hypothetically) more likely to give good advice, as they most likely know a good deal about computers. In this case, I can’t honestly recommend Linux, as my personal favorite tool (Dreamweaver) is not available on Linux, and it is too complex to be run in WINE.
I honestly have to recommend Windows in this case, as there are fewer widely used web browsers compatible with OSX (and the one that you most need to test is ONLY on windows). Both OSX and Linux have crappy Flash support, so if you want to do flash you’re kind of outta luck.
Buy at the same price you would spend on a Mac and you will be just fine.
I take it you have never encountered a true Linux fanboy. Or are you rounding and predicting that 1% will be Linux fanboys?