When does something become obsolete? I suppose the simplest definition of the word is when that thing becomes completely useless.
I collect old Macs. The oldest one that I own is a Macintosh SE which was manufactured in 1988. It is nearly as old as I am, yet it still functions perfectly. While are networking cards available for the model of Mac, this Mac does not have one. The computer cannot connect to the Internet directly, which we generally consider to be the benchmark of usefulness for modern computers.
The Internet, however, is not the only way a computer can become useful. I used my Mac SE to type out this blog post. Granted, it was necessary to transfer the file to a more up-to-date computer with a high speed Internet connection and blogging software. All I needed to write this blog was a 21-year old computer, an 800L floppy disk, Microsoft Word 4.0, and an ADB keyboard and mouse.
My attachment to old things does not end there. I have been driving a 1986 Honda Accord for the last five years. More than three of those years were spent commuting twenty-five miles per day between home, work, and campus. I have not moved on to a car that was built more recently because there has been no need for me to. The car that I drive right now is still perfectly suited for the task that it was built for.
My car consistently fails to break down and always gets me to where I need to go. My old Macs provide me with a distraction-free place to get some writing done. I suppose my point is that it does not make sense to throw something out or replace it if it still has utility.