[quote name='shockblocker']How is Impulse's policies compared to Steam or Games for Windows. I went through the FAQ on the website and it seems a little shady. Can anyone vouch for them? I don't want to get stuck with a lot of annoying charges and nagware for a 1 dollar game.[/QUOTE]
Impulse is one of the main, big DD sites -- though nothing compares with Steam in size. It's been around a few years and is owned by Stardock, the developers of GalCiv.
I've bought a few titles from them, and they're alright. Impulse, their client, is a bit clunky and does popup ads for their sales (until you turn off the "Impulse Now" tray icon), but it works. The client isn't needed to play the game, so you can uninstall it after you have the game downloaded/installed, if you want. You get unlimited redownloading as long as they exist, the client does patching for you (not that further GalCiv patches are too likely), all the usual stuff you'd expect.
One nice advantage of Impulse is that it lets you backup your games in a manner which allows you to restore them without needing to login to Impulse -- it just creates a .7zip file encrypted with your username as the password. I think GalCiv requires internet activation after installation, but for other titles it's a nice way to make an offline backup.