If it's backing up and DRM you're worried about, it might be worth checking out
GoG. You need an account to buy stuff (of course), but there's no client software you need to install to play. Downloads are supplied by way of an installer EXE, so you can burn that to a CD/copy it to a pendrive/whatever and keep your own hard copies. Not as aesthetically pleasing as a shelf full of cased games, but adequate for making sure you'll always have them.
It does have optional client software, but AFAIK that is basically a download manager and nothing more. I've bought about 4 games from them and never used it.