Yes, it's true. Over the next two years, Apple plans to introduce new Macintosh products based on Intel processors. They will not simply drop the PowerPC, but rather they will transition to it over time. Not all of their products will transition at once--in fact, reports indicate that Apple's PowerMac is unlikely to be replaced by a Pentium chip for some time yet.
Apple and IBM cite different reasons for Apple's decision. Steve Jobs reports that IBM, the makers of the G5 series of processors, has failed to deliver either the mobile G5 or the 3GHz G5 he promised developers two years ago. IBM's version blames Apple for being unwilling to invest in the creation of these new processors to its satisfaction. Probably both are accurate but incomplete accounts of the negotiations between the two companies.
Supply chain issues have been a problem with PowerPC chips for quite some time. Motorola (now Freescale) had trouble meeting Apple's demands for the G4. When Apple announced the G5 processor made by IBM, Mac users cheered. We thought this would be the end of the processor shortage for Apple. We were wrong. And now IBM has three customers in the form of the three big gaming console makers, all in line ahead of Apple for its products.
If you want a Mac now, buy a Mac now. Seriously. This transition is going to take a few years. Next year, the first Intel-based Macs will be released. Probably these will be low-end machines like the Mac mini and iBook, using the latest Intel processors in the same family as the Pentium M. It will be at least another year before the rest of Apple's product lines see Intel processors, and probably at least another year beyond that before you begin seeing features that require an Intel-based Mac.
What this means is that your current PowerPC-based Macintosh is not a doorstop. A new Mac is just as good today as it was two weeks ago. If you still are looking for buying advice, I would say don't buy any Mac you're not prepared to upgrade in about 3-4 years. Keep in mind that this coincides with the typical Mac upgrade cycle. (You read that right, PC users, we're used to having our computers much longer than the 18 month to 2 year cycle so common in the Windows world.)
I personally won't be buying a dual 2.7 GHz PowerMac G5 today, but the dual 2.0 and 2.3 GHz machines are possible targets if I were upgrading my workstation today.
Apple says that MacOS X will always require a computer made by Apple. The current software license agreement prohibits you from running MacOS X on any non-Apple computer, although standard PowerPC boards are available that will boot MacOS X just fine today. Although the final hardware used by Apple in consumer systems will likely be more custom, Apple will be leasing Intel-based development systems in G5-style cases with apparently-standard Intel mini-ATX boards in them for $999.
It should be possible. Don't expect Apple to make it easy or to support it if you manage to get MacOS X working on your machine. The Macintosh experience is intended to be a package deal. Let's face it, it's hard to find a Dell with all of the features we take for granted on our Mac. Firewire is largely shunned by the Windows-using world, for example, and Firewire 800 is almost unheard-of. Apple was first with USB, first with Firewire, first to actually use Serial-ATA in a computer you could actually go out and buy.. Basically, Apple makes computers with a lot of standard features that others offer as options, if they offer them at all.
So the answer is that it's technically possible, but perhaps not necessarily the best thing to do.
Apple doesn't plan to ship Windows on its Macs, and doesn't intend to support users trying to run Windows any more than they currently support users running Linux. Apple is sure a few people will buy Intel-based Macs and install Windows on them, though, so it should at least be possible.
No.
No.
Because we've been answering the same set of questions since June 6th. Always from Windows users who haven't watched the WWDC keynote, even though it can be viewed here. It doesn't help your cause any that some of the people who have joined us have not exactly been shining examples of the Windows user community. Together, these factors combine to form a very low tollerence for people who missed the announcement and associated details.