Wow... I became a member of steam after I went to three area brick and mortar shops to get left 4 dead, and NO ONE HAD IT... 3 MONTHS LATER! Actually, one store did have it. It was an opened display copy, being sold for brand new price. "Um, that was opened, don't I get a discount for it being an opened display copy?" *Chuckle* - "No, it's brand new" Ugh... gets me fired up just thinking about it.
Point is, it's been almost 10 months, and I have about 20 pc games now through steam. The only games I ever bought before then were BIG titles. I didn't play any other games (didn't pirate, didn't buy, too much of an investment on something I wasn't sure of).
Best Example: World of Goo. Steam had a sale, the game was $5, normally $20. I thought why not? Best decision ever. Opened me up to Indie games. More recently: Sword of the Stars. I had a copy of it on my computer, never bought it though, I couldn't get it anywhere. I was ecstatic when it showed up on steam, and dropped the cash for the master collection. I know the developer was excited, their sales skyrocketed because of Steam.
P.S. EA Download manager SUCKS! I HATE messing with it, and would ditch it if not for BF2142 and Spore