Crassmaster: Steam isn't feeling any heat from ANYONE right now in terms of digital distribution. While Impulse, Gamersgate and Direvt2drive might be having a pointless little pissing match over who is in second place, they all admit they are so far behind that it doesn't really matter.
And since the majority of Steam's business is in new games or bundle deals, they aren't feeling any heat from GoG, either. All it comes down to is what people want to buy. If they've heard from enough of their users that those users want older games, that's why they're making an increased push to get them. I also wouldn't be surprised if the publishers are bringing it up. Maybe Kalypso brings up some old stuff in their catalog when Steam is working with them for Tropico 3, for example.
Despite my beefs with them, Steam is and has been my primary delivery system, but I only buy games for $20 or less primarily. I believe the most expensive of my 135 games was L4D on sale for $25. I like GOG, and I have a LOT of issues with Steam, but I still have a lot of faith in them, and I am willing to give them time.
Impulse has many of my "wishlist" features-wise, but for some reason I am wary of them. I cannot explain it, but there is something that worries/bothers me about them. I only buy from Stardock when it's a blockbuster deal, like the Corporate/Political Machine at $2 each.
I like playing mnay older games, but GOG has a LOT of games I would not evne CONSIDAR playing. Outside a few exceptions, I have no interest in any games older than 1999 or so. I do expect certain a certain technological complexity, and thankfully GOG does have a lot of 2000's games well worth playing, Empire Earth, Imperial Glory, and Beyond Good and Evil to name a few.
One last thing about Steam, I LOVE Steam achievements, and the community overlay. I never thought I would like achievements, but they really do add to a game, and the way Steam does it DEFINITELY trumps the way Xbawks does it.