Brother Wands

okay i cant rember it proberly but i rember something along the lines of a wand from the same phoenix cannot kill its brother or something like that correct me if im wrong so if harry has to try and kill voledemort wont he have to do it another way.
will he have to find some new powerful wepon to help him or will he just grab rons wand and bam

Yeah, because Harry and Voldemort share the same wand core from the same phoenix, and like we saw in goblet of fire they don't work against each other.

perhaps this will be important in DH, it might be that voldemort has taken ollivander to make him a new wand so that he will be able to use it against harry

Yeah, that is right. The two wands couldn't defeat each other. When they did try, it resulted in the outpour of the souls that Voldemort had killed (Goblet of Fire). However, Harry did use his wand to kill Voldemort, it only worked for one reason. When Draco disarmed Dumbledore, the Elder Wand was passed to his ownership. When Harry was escaping from the Malfoy Manor, he disarmed Malfoy's Hawthorne wand...not knowing that the Elder wand was now his. Voldemort thought that the wand was in Snape's ownership, so he killed him for it to be under his control (Even though it was actually in Harry's). In Deathly Hallows, Voldemort used the Elder Wand, not his Pheonix. Harry used Expelliarmus, when Voldemort used Avada Kedavra. The Elder Wand won't kill it's own master, so the spell rebounded and hit Voldemort. Does that even make senese?!