QUOTE(cambiata @ Feb 5 2009, 08:41 PM)
Would someone be kind enough to explain to me the essential differences between a Mac and a PC because I have absolutely no idea.
they run completely different software - PCs run Microsoft Windows, and Macs run MacOS. generally, people seem to find MacOS easier to use than Windows, and that things "just work" instead of requiring a lot of fiddling.
the downside is that because MacOS doesn't run Windows programs*, you can't use your Windows software on MacOS (except for a few programs that run on both, like Adobe Photoshop or Cubase). but, if a particular piece of software exists for Windows, it's likely there's something comparable for Mac.
in the past (before 2005 or so), Macs also used different hardware from PCs, but nowdays, the hardware is pretty much identical, to the point that you can run MacOS on a PC (although it's technically illegal), and run Windows on a Mac.
historically Macs were very popular for music, imaging and graphic design, and similar "creative" purposes; at one point, you could almost guarantee that in the publishing room of a magazine you'd find Macs running Quark Xpress. for a while they were falling out of favour compared to PCs, but thanks to some very good marketing by Apple, and some updated software, they've made a comeback in the last 10 years or so.
i'm not sure why a Mac would be better for someone with poor eyesight, though; i'll let tony answer that.
* before anyone pedants me, i know you sort-of can ;-)