restorecd

yes i recintly purchase a computer htru a third party computer vender it is a hp vectra vl400mt i acidenaly downloaded a restore cd for a dell with windowsxp pro i had winodws 2000 pro but the people whom i purched the computer did not give me a retore cd .question i have is where do i go to get a restore cd and will it replace my operating system that was originaly on my computer since this is a hp and the softwrae was for a dell computer also the software will not unlock the key to activate is this because it was made for a dell computer all answers welcome