Samurai717
CAG Veteran
cool list of games 
i have read on here that someone was able to do that, but I personally have never tried. What I have done is actually get the game that I pre-ordered, and when I pick it up ask for a gift reciept (which doesn't show that the game was bought through a trade-in deal). Later, return the game with the gift reciept and you can get the full amount of the game (plus tax in some places!) put back onto a gift card.
If you go that route, try and get a gift card with PIN on it, so you can use it online and join in the fun of the eb morning update thread without spending cash money.
When you go cancel the pre-order, don't take the receipt that has you traded games on it. simply tell them your phone number and give your ID and they'll see your pre-order in the system. I don't think that the system shows that you used a deal to pre-order, it just shows the amount you paid and the game you preordered.
I used 3 more games from Gamerush (they are just about out of $6.99 PO games now ) today to put down a NASCAR preorder. If I can't switch it I'll just trade it back in to GR and hopefully get $35 + the 25% bonus.
I used PS2 Breath of Fire Dragon Quarter, Xbox Starsky & Hutch, and PS2 Kya Dark Lineage, along with a GC Rocky from TRU (for $5). So $13.98 in GR credit and $5 cash got me the preorder. Not a bad deal no matter what I end up doing with the game .
I really wish they'd extend this type of deal to some other games though - it would be nice (as with Nintendogs) for there to be some games I actually want to play. How about Mario Superstar Baseball or the GC Fire Emblem?