what is the best computer for my elderly parents? - pc touch screen

My 70 s parents finally connected to the Internet via a rather older laptop.
Due to the lack of several keys on the keyboard, they connected another keyboard and one mouse.
Both are far less clever than before;
My father has Parkinson's disease.
My brothers and I are thinking about getting together and buying something that is easier for them to use and here we are separate.
There is a brother who thinks we should look at the tablet although the rest of us think it is too small because their eyesight is not very good either and my father may have a hard time using the touch screen.
They may only use it for email, very limited web browsing, and Skype.
We have a budget of 350.
Claire Whitfield pointed out by email that the problem of screen size and touch screen sensitivity on the tablet is something that can be overcome, but I think in the end, one has 15 or 17-
Inch screen, will involve minimal turbulence and remain within your budget.
I will be shortlisted for the model that comes with Windows 7, which is not much different from XP or Vista, and currently there are some attractive deals on models that have been discontinued recently.
More importantly, W7 has a wide range of built-in products
In the accessibility options, it is designed to help those with a variety of visual and physical impairments.