I've researched on here ad much as I could but haven't find the exact answer ok looking for, I bought the xbox 360 4GB Sunday and that night playing 1 game I filled the HDD, I should have done research first online but didn't due to an associate at best buy already answered my question, so I thought, apparently you can't hook up an external HD to the system tostore game data only media, so I want to bring back system on Tuesday, so only 2 days later and exchange it for the bigger more expensive 250 GB, now I've never had issues, cross my fingers, with best buy but i'm hoping especially since I want to give them more money that it'll be okay. I'm sure .by the time someone responda I'll already been through it but just in case id like to know the policy