Windows 10 is coming out this summer which will bring back the start menu and should be a more familiar experience to Windows 7. So if they can wait until then you might buy a desktop loaded with it, but you can also buy a windows 8.1 desktop now and windows 10 will be free to upgrade when it comes out for the first year.
HP has a couple options for desktops that are pretty cheap, if this person doesn't need a lot of processing power power or space and just wants to do time office stuff and internet exploring the HP stream is 180 dollars and fairly stripped down (32 gb internal storage expandable through sd card, 1.47 ghz processor, 2 gig ram) and will be upgradable to windows 10 when its released
HP also has a Pavillion Desktop that is really small like the stream but better guts (500 gb HD, 4 gb ram, 1.7 ghz processor) for 380
I think chromebook would be a bad idea, its easy but its way different than a windows computer and if windows 8 is frustrating for them chrome os will be a nightmere