Giants/Dallas is a 1 PM game; for your best bet - get there at 11:00-11:15; stand on the right line and wait for the first come first serve seating in the bar area; if you get a booth, they will come around and ask you what game you want on the screen in your booth. They put audio on for 2 different games, 1 in Sports Central (the side with the big screen, where they seat you) and 1 in Sidelines (bar area).
If you don't get a booth table, look at the monitors all around the club, and find a table with a good view of a TV that has a little Giants flag on it, that's the TV they will be showing the game on.
If you are really concerned about the audio, and it is a possibility that the NYG game will have the audio as 1 of the 2 'better' games of the week at 1 PM, then call the night before, as late as possible, to the ESPN Club and ask which side is going to have which audio. Keep in mind they may change it at the last minute; they do come out right before the club opens, however, and when you're standing in line let you know which room is going to have which audio.
Go Big Blue!!!