Well, I am going to go against the grain here, and argue that the basic "grandma" computer doesnt really need an SSD. I use multiple machines at my work and even my home desktop does not have an SSD. None of those computers feel "slow" to me in casual usage. Now might they boot 30 seconds faster, or open a program in 3 seconds, instead of 10 with an SSD. Of course, but does it really matter for an occasional user who just goes on the computer briefly a few times a day? And even regarding boot time, just let the computer go into sleep mode. Now when I am sitting there waiting for a level to load in FO4, *that* is when I wish I had an SSD, or of course if you are doing productivity tasks that do a lot of reading and writing to disk.
And Please, Please, Please, stop posting advice to buy atom systems. They are pitiful in a desktop or full size laptop. I would take a HDD, even the slowest possible one, with a big core cpu over a tablet processor in a desktop any day.
Now before I get ripped a new one, with SSDs getting cheaper, for a light use computer, it *would* make much more sense to include a small SSD instead of a 1TB hard drive. But I just dont think a "grandma" user is going to be dissatisfied with any modern big core desktop.