Agree. I Installed Ubuntu to my girlsfrind and it was running 1 year without destruction. On the other hand I've taken away administration priviledges from my dads windows 7 and its holding pretty well ...
It isn't a matter of comparing like for like; that isn't the problem. The problem is that the single cheapest Mac laptop is $1000. If all you're doing is web and email, you may not need a Core i5 or SSD. You can get a PC laptop which is more than fast enough for Mom usage for less than half that price, especially if you put Ubuntu on it and don't have to run antivirus.
"It isn't a matter of comparing like for like; that isn't the problem."
Never heard that in a discussion. I thought it was all about comparing like to like. The OP didn't say "for reading emails". Especially as he gave the example of 100% Office compatibility (Office 2011?).
Or you could compare live time value. I've broken several Thinkpads in a small amount of time, my wife uses a MacBook for more than 5 years with the newest operating system and applications.
Or, if you need email, only use a phone. Or if you only surf the web, buy a tablet. Or if you only do small amounts of web and email, don't buy anything at all and go to a free library. It depends.
But the argument was that a Mac laptop is much more expensive than a PC laptop for working with Office. Which it is not to my knowledge.
If you don't need it, don't buy it - no argument there.
Is your premise that you need a Core i5 to use Office? That seems like a stretch. You can get Core i3 or AMD A-series laptops in the $500 range which are more than fast enough for Office and still half the price of any Mac laptop, e.g. this one:
A PC of equivalent power and build quality has a roughly similar cost to a mac.
If you're willing to cut back on the quality and capabilities there are very cheap PC options, but no very cheap Mac options. For someone who just wants to browse the web and edit occasional documents there is a lot of cutting back that can be down.
And don't forget to factor in the anti-malware package, the extra gigabyte of memory it'll take, the beefier processor it will demand and the beefier battery you'll need to run the whole thing.
