If you prefer your PC games to be shipped in a retail box, then GoGamer.com is the place to go this weekend. They are running their regular 48 Hour Madness sale and as usual have some big markdowns on a number of PC game titles.
This weekend you can get games like Supreme Commander for just $6.90 and Just Cause for $2.90. Half-Life 2 with Deathmatch is just $7.90 this weekend and the more recently released King's Bounty: The Legend has a price point of $22.90 at GoGamer (compared to its normal price of $39.99). That's just some of what's on sale this weekend on the site so make sure you check it out in case you see a deal you want to take advantage of.