Greetings

i recently bought myself a mac book 2 months ago, i dont kno much about computers. I then wanted to install Win XP but my boot manager was refusing. since i had nothing in my computer, i formated it, partitioned it, installed the OS X first. I then tried to install XP which formatted the whole drive. So i had to re-install my OS X again. So what happened is that now my HDD is no longer called Macintosh but "Untitled".

Its not giving me any problems now but i am afraid it will giv me in the future may be for some installations or so. My question is how do i get my HDD to be called "Macintosh" again without formatting my mac book.

Thank you