Good Old Games.com is a site where you can purchase older PC games online. The UI is manageable, the prices are great with frequent specials, and most importantly the games actually work. The biggest problem with playing many older PC games is that they were designed for obsolete hardware and end up requiring some random ram nobody's ever heard of. As a bonus some games come with extras like wallpaper, soundtracks, and so on. It's probably not something you couldn't already find on the internet but it's still a very nice touch.
Right now you would do well to check out the Interplay special as there's a buy 1 get 1 free sale going on. This includes lots of classics like the Descent series, Freespace, Fallout, and many more. The Might & Magic 1-6 Collection has also been released which is a bargain at $10.
Of course I just found out that my laptop is so fried it can hardly run any of these games. Such a waste. As it stands I have to figure out whether I want a new PC, a J-360, a PS3, or an HDTV.