First things first... Do you have all the necessary XP drivers for your system? If not, you should stop right now, because you're not going to get XP up and running on that system.
Also, this is going to sound very offensive, but it's not meant to be... Given the level of computer literacy you've demonstrated in this very short message, I would say the odds of you successfully installing Windows are slim. Not necessarily anything to be ashamed of. I'd much rather the doctors of the world spend their time keeping current on medical advances than learning the ins and outs of computers. Same with a number of other vocations.
I'd say you have little chance of installing XP on that system, so I would suggest just learning to make the best of Vista. It's really not all THAT bad, it's mostly just different from XP. Don't think of different in terms of good or bad, simply being, and a lot of things in life are much easier to deal with.
when i bought my laptop,i think i came with vista or maybe they upgraded it there....but now,im trying to install xp but i can't click the install xp button....is there a way for me to remove vista and then install xp?