The Thinkpad T43 is also an ancient computer. I own a four year old Macbook Pro. I can tell you that it has more crashes than all the Windows 7 machines in the house put together. Most of the problems are due the old age of the laptop, not any fundamental flaw in OS X or the Macbook design. Software in OS X also requires software updates, as does OS X itself. Luckily, the most modern operating systems keep software updates mostly in the background. You will be asked by the App Store or the software itself for you to update it. Then it keeps itself mostly in the background. Updates like this are no more of a problem in the two newest versions of Windows than they are in OS X, at least in my experience. Nothing is going to be as bad as Vista, for instance.
Windows 8 is probably the quickest booting operating system around, at least provided you have an SSD. However, I think most people just put their laptops into sleep mode so it shouldn't matter too much.
This depends on who you ask. Plenty of people that I run into dislike the update from iOS 6 to iOS 7. I know that several buggy features have been introduced in paid OS X updates. The fullscreen mode in OS X has been horrible for multiple monitors since it was introduced, and it will require another paid update to be fixed. I've had programs that stopped working completely after upgrading from one version of OS X to another, if I recall correctly it was the Lion update.
I'm someone who uses both Macs and PCs. My main laptop has been a Macbook Pro for the last few years. The biggest advantage for me is that Apple's laptop hardware is very nice. In the four years I've been using a Macbook there have been some big improvements in the PC market, but it's still hard to find a Windows laptop that is as good a package as the Retina Macbook Pro or 13" Macbook Air.
