Re: The curse of overchoice
"If anyone can point to an ISO that would work like a Windows install disk would, I'd be very grateful."
Well, yes, but also no. The Linux and free software world is all about freedom of choice, rather than meekly having to accept what has been provided for you. It's evolution in action, in a way. That is just the way it is, and it's not necessarily a negative. What works well, or is popular, flourishes; what is less so, either finds a niche or perhaps gradually fades away.
Yes, I realise that this doesn't help you choose what species of animal you want to have as a pet, but you approach it in a similar way: find friends with a variety of pets (or look at reviews or videos online), and see which one you think you like the most. Or, as most people would probably do, they'd consider an "ordinary" pet such as a cat or a dog, rather than a gecko, gentoo penguin, pufferfish, jaguar, red panda, etc… (Although, if you know what you are doing, you can have a more exotic pet. It's the same with Linux.)
But if you want a suggestion, just pick either Linux Mint or Ubuntu and download their default LTS (long term support version) installer (OK, that's two suggestions). Either is perfectly suitable for new users, and their current level of popularity probably means that you are more likely to be able to get help for these easily, if you need it (although the same also applies to most of the other "well known" distros almost equally well).
With many installers now available as "live" bootable media, you can also just load it up and play around with the desktop environment included in the installer for a while before deciding whether or not you want to install this version on your computer for real.
If you decide that you don't particularly like the desktop environment that the distro has chosen (eg, Gnome 3 that comes with the default Ubuntu install is more like MacOS (or perhaps Windows 8 done in an actual useable way), but may not be for everyone), you can fairly simply install the package for a different desktop environment instead, and select to use that the next time you login. You don't need to reinstall Linux all over again to change your desktop (although the "recent" trend of providing a range of installers based around specific desktops perhaps unwittingly does give that impression to some extent).
And, if, even later, you decide you don't like the distro you have installed, then you can choose another and install it (and restore your data from your backup, or, possibly, if you are careful during the install, be able to retain your /home partition and just reuse it). But the choice, of course, is yours.