My samsung behold is freezing and turning off randomly.!?

i got my behold for christmas..december of 08 and i was wondering if i could take it back and get a sidekick lx 09 orchid??but i dont know if im still on warranty or not..if im not how much will it cost and if i am how much will it cost??or can i get the sidekick as a replacement??please help.!and thank you