Hmm, this certainly has a bit of misinformation here. First of all, the FTC can only step in if there is an emerging monopoly. Unfortunately OSX isnt the ONLY other operating system. Even though all the different linux solutions, and small OS's dont seem like a competitor, they technically keep microsoft from being considered a monopoly, even in the abscence of OSX. The same goes for intel, if AMD went out of business, there are still companies such as motorola and transmetta that would keep them from violating anti-trust laws. The original anti-trust suits from microsoft didnt even have anything to do with windows, it had to do with the way internet explorer was integrated into the OS.
Also, on the issue of Jobs keeping microsoft from purchasing Apple? If i have my information straight, i dont believe Jobs has a controlling interest in Apple, he may have a large portion of stock, but i dont think he has enough to keep a takeover from happening. A CEO has little to no say if a company can be purchased if the stock is publicly traded. The honest truth is that since apple is a strong company, and microsoft is a behemoth, chances are that M$ would have to pay such a premium for apple as a company, shareholders would be more than happy to sell their stock for such a great price.
Will it happen? Probably not likely, the cost would be so high (probably close to $75-100 billion, that they'd have to give up too much cash and cut funding to their own projects. But all things considered it isnt out of the question, look at AOL and Time Warner, or Cingular and AT&T.