Xbox 360 backup hjelp?

[santalos5]

My xbox 360 got flashed a long time ago by some guy I payed, If I were to take backups and play them on my xbox, would it work, or will I have to update to the newest iXtreme firmware (or whatever firmware that guy put on my console) to be able to play?

 

Also, should I update, if so, why? Btw, I alredy have some backups on my xbox, but they are old (l4d2, mw2) except black ops. You've probably figured out that im a huge noob at xbox, so an explanation would be appreciated