Start watching the Steam, Humble Bundle, and GOG sales daily for inexpensive games that you will probably never play. Soon you'll be like the rest of us with a backlog hundreds of titles long!
oi... don't tempt him to the dark side :( that place is so sad to see, specially if you shop for 60+ hour games all the time.
@kaos_cracker: whatever genre you enjoy, PC exclusives are a bit rare these days it seems, at least in the AAA segment. If you're looking for smaller budget titles or Independent games, you're going to find a lot more.
And ports, well... I go ahead and toot the horn for http://pcgamingwiki.com/wiki/Home . Might be a nerve safer later on.
Store wise: @mb called out a few already. There is a humble store now too and Paradox Interactive also has a store (Gamersgate) and there is also Greenmangaming who sometimes offer some good discounts. Please note that I haven't used greenmangaming at all and that in most cases you end up with a steam key regardless.
And there are of course the "glorious" lands of free to play titles.
Posting a list of preferred genres or games you enjoyed in the past would probably increase the quality of the recommendations you might receive.