I will only comment on one part of your post:
Yes. There are many folks who would love for this to happen, but in my opinion it would be terrible. Microsoft does almost as much to drive innovations in the field of software development as the entire open-source community. You may not agree with their motivation, but you gotta love the end result...
What were the innovations over the past 2 years developed by the OS community?
If Microsoft were to "go away", there will be much fewer software options than currently exist. For example, .NET is a great development platform; SQL Server is an excellent relational database. I don`t know about you, but I personally would hate to lose either of those options. Sure, something else will take their place; but I`d rather not be forced to use Oracle or Postgres or whatnot... I like my SQL Server! 
Microsoft also does a great job of providing resources for developers who work with their platforms. There is no equivalent of MSDN in the open-source world. (Though I will say that for some reason, the overall quality of MSDN resources has declined greatly in this past year).
Finally, it`s naive to think that if Microsoft ceases to exist all the malware and spam developers will just curl up and die. The reason most malware today is targeted towards Windows users is because they are such a heavy majority - so the "hackers" get more bang for their buck, so to speak. If MacOS or Linux were ever to become the predominant OS, you better believe all the malware kids will be learning new things in a hurry. Right now it`s just not worth their effort to write virii for Macs beacuse of how limited the target audience would be.
Hackers have a principle? That`s news to me! 
Maybe you`re talking about today`s hackers... If the next generation of computer users will primarily use Linux, I would bet money that the next generation of hackers will be writing Linux malware. That is just the way of the world...
mySQL is perfectly fine for your everyday e-commerce site. How many enterprise-scale applications running on mySQL do you know of?


Well... I`ve worked for a established & successful company that provides enterprise management software used by municipal and county governments, police departments, fire departments, courts etc. all over the US.
They offer 2 products: IMB mainframe, and web-based (MS .NET, SQL Server, IIS). No Linux, no open source. The company is a partner with both IMB and MS, and so they always end up using the latest & greatest cutting edge software from both companies.
I suppose it is possible that no one in this company and none of the clients they serve watch the news, or just don`t know any better?
Sure there are known security holes. But they exist on every platform! The MS ones are just more well known because the hackers/phishers/spammers/whatever you want to call them concentrate all their efforts on going after MS platforms. If you are a hacker, would you rather write malware that could potentially reach 80% of the internet users, or 5%?
By no means am I advocating that everyone use MS software only. (Though if everyone used IE, it would make my life as a web developer much simpler!
) If mySQL works for you, that`s great. But why would you want to see some of the available options dissapear? Sure MS produces some crap; they also produce some great products. In my opinion, the great products outweight the crap by a large margin. I honestly believe SQL Server 2005 is the best relational DB on the market today. If you don`t need it`s advanced capabilities or can`t afford the price tag, there is absolutely nothing wrong with an open-source solution. But do you really want it to die just because you have a bone to pick with the way Microsoft runs their business?