As you can tell on our site, we sell a lot of older Macs. One of the beautiful things about Macintosh is how well they hold their value. It takes a very simple mathematical equation to determine that Macs are almost always cheaper than their PC counterparts. All you have to do is factor in the trade-in value of the Mac at any point down the road. Windows-based PC's are usually worth nothing after just a year or two. Macs have good value for many years past that.
In addition, you can't run Classic on an Intel Mac at all (or any Mac running 10.5 or higher), which is why there remains strong demand for PowerPC (G3, G4, G5) Macs today.In any case, there are generally three types of customers for the older, pre-Intel Macs.
The first are those who need to run Classic apps, or are simply replacing a Mac and they prefer to replace it with the same generation of Mac. Those people usually know exactly what they're doing. With Apple's support of Rosetta on the wane (which is the software that allows applications compiled for PowerPC processors to run on Apple systems that use Intel processors), the availability of PowerPC Macs may be essential for these people for quite some time.
The second type are those who are looking to add a Mac to do non-intensive work: surfing the internet, doing email, etc. It might be a computer for a youngster or just a low-demand user. Much of the time a pre-Intel Mac will work just fine for that purpose.
The last type are those who are looking to buy their first Mac and want to save as much money as they can. For you, we would offer up some information as well as a few points of caution to ensure your Macintosh experience is the best possible.
So if you're buying your first Mac and you're considering a PowerPC, you should understand that many of the latest applications won't run on that model of Mac. You can still sync an iPhone (if its OS is prior to iOS 4) as well iPads and iPods with earlier versions of iTunes. Note that the latest iTunes works under 10.5xx (in fact it requires it or above). That means you can use the latest iPods and iPads but only as long as your G5 or G4 has USB 2.
Another interesting thing is if you were to update your iPod or iPhone on an Intel machine with the latest iTunes, it wouldn't be possible to update your iTunes on a PowerPC thereafter; your iPhone or iPod firmware version wouldn't match with your iTunes version. It is also impossible to roll back your firmware to a later version, so under that scenario you wouldn't be able to sync your iPod with your PowerPC Mac.
Suffice it to say some interactions with iPods, iPads and iPhones will work, but the whole experience may be problematic, especially if you want to use the latest versions of everything.
Also note that most high-end apps (Final Cut Pro, CS 5, ProTools and even Microsoft 2011) require an Intel chip. Netflix's streaming support requires an Intel chip. Many games, including the online games, and most of the new browsers require an Intel-based Mac OS 10.6.7 (which the Mac App Store requires) requires an Intel-based Mac. You need an Intel chip in order to run Windows on a Mac as well. As new software is developed, the list grows quite long.
And so again, if your computing ecosystem tends to have older software, you need to run Classic, or you know exactly what you're doing, the PowerPC Macs still have great legs and will perform well for you for quite some time. We just want you to be aware of everything going on in the computer industry so you make a well-informed decision that suits you perfectly!