I have never had a problem getting a game when I go to the store, but I have noticed more people preordering games so that they are sure to get them immediatelly.  When you make a pre-purchase of a game at Gamestop make sure you ask about your “In-Game Perks” if there were any to be given.  Recently when we purchased Battlefield Bad Company 2 they had put the extra codes on the receipts that come off of the epson receipt printer.  With Battlefield the preorder people actually got 2-3 items extra, and for preordering the V.I.P. edition we also got to get the map packs for FREE.  If you don’t see a code on the receipt, then ask.  The other thing that they may give you is a cardboard card with the addon code printed on that.  For the most part pre-ordering a game just guarantees you that you will have yours on the release day for the most part.  I remember the one time I was on vacation in Florida, and tracked down a Gamestop so I could preorder Call Of Duty.  Going there a few days later paid off because the line was out the door, and around the corner.