Two things are wrong with your story.
#1: You are NOT legally allowed to use the install disc from one computer on another
#2: You have a SATA hard drive, and XP has no concept of that on account of it predating SATA
Now, #2 would potentially be fixable, but #1 I'm afraid means we've reached the end of the line on this discussion. Find the original discs, order a new set from HP, or go buy a new copy of Vista or 7. Those are your legal options.
Ok so I a hp pavilion dv900, that's been siting in my closet for like a year, because the screen broke, so I took out the 2 HD that it came with one toshiba 120gb and the other is a seagate 120gb. Well I been using them as external he's and the toshiba one broke on me, and I recently found out I can just conect my laptop to a monitor and use it that way. My prob is I went to best buy and got a wd scorpion blue 320gb SATA notebook hard drive, I put it in and I used the bios diagnostics to see if it reads and make sure it's all good. Ran the smart test and it passed and it's all good, but when I went to install the os on it I mus of lost the original os cd, so I used a different one from a desktop I have and it has xp os, but the laptop had vista. So I put in the cd and it says to reboot from cd press any key blah blah blah, I get to the part where it asks if you want to install windows press enter, so I do and it gives me a MSG saying no hard drive has been detected or something like that. So I don't know if it's something with the computer, or I need the original vista os on it, I'm not sure what the problem is, because the bios reads the hard drives and does the diognostics on them and comes out good but then when I try to install xp os on it, then it doesn't find any hard drives. If anyone has any help, thanks. And sorry if I misspell anything I'm on my itouch