From a technical standpoint, Microsoft has implemented a totaltarian regime. They maintain absolute control. I've done quite a bit of programming in their environments and it IS frustrating. One can spend their career waiting for the next release.
Open Source is a free market of ideas. Anyone and everyone is free to contribute. The resulting products are more feature rich and robust. The competition of ideas and excellance has lead to the most secure systems available today.
The business model is different between the two. Microsoft requires you to upgrade hardware and software regularly for them to remain profitable. Open Source gives you choice: there are still many Linux 486 servers out there on the internet. If all you see is a US Corporation under 'attack', consider at this point Microsoft probably has more staff lawyers and accountants then programmers on staff in the US at the point. Gates is a democrat and he runs his company like one.
Don't forget: FreeRepublic runs on perl - a language that has always been and always will be Open Source.