The problem is that Sony don't have a product like Windows, which is something that gets MS a LOT of money, for a proportionally inexistant cost.
Sony makes hardware, each unit they sell cost them money, either it's a TV or an MP3 player or a PS3. They need to pay for R&D and for the materials in every single unit, plus manufacturing costs and lots of patents i suppose.
MS sells Windows and other programs at stupidly high prices, considering how much it costs them to sell one unit. After the cost of R&D for developing the programs and OS's, the only cost they incurr is the packaging, and i don't need to explain how cheap a box and a DVD (sometimes a CD!) is. And sometimes they get multiple times the same licensing fee from the SAME box anyway (like for offices, you only need one copy of Office, but need to pay a license for every computer you install it on).
That's the big difference between a hardware company and a software company. That's why MS can afford to bleed much more than anyone else, they will always have Wondows/Office to feed the black hole.
Sony only have their profit margins from their very overpriced electronics, which haven't been selling like hotcakes lately anyway - apart from PS2, which doesn't have much of a profit margin anyway.