chirath

Hello everybody. I'm new to Xbox 360 series but i used to play Xbox original for a long time. I brought 360 old (white one) with RROD and tried to fix but couldn't. It has a 20Gb HDD. then i brought a 360S (second hand again ) for a very cheap but did not get the controller and Hard disk. this supposed to be 250GB hard disk how ever i swapped with 360 old 20GB hard disk and it works fine at the moment. when i purchase xbox 360 s i got a game DVD - Sniper ghost worrier"and its works fine. after that i got NSF under cover but it throws me an error saying wrong region . when i check the covers and disks Both DVDs are PAL and when i insert that NSF CD in to my PC , it detected as NTFS DVD, both are original Xbox DVDs. what is the issue here? is i can see orange line of serial number sticker on back of my Xbox and is there any other way i can check DBD and console in which region also how can i swap a new HDD Thank you Chirath