[MrForbes]

The HP laptops usually have two partitions, one is the recovery and the other is the normal system partition. You should be able to install xp without changing partitions, it should ask during setup which partition you want to install it on, and whether or not you want to format that partition. If you save the recovery partition and don't mess with it, you should be able to reload Vista later if you want to. It will wipe out all your data, so you DO need to back up ALL your data!

It's been a month or so since I installed XP though...and my memory isn't as good as it should be...but it seems to act just like windows 2000 during installation....

You'll need a full installation disk and key for XP. Not cheap, unless you luck out and find it at the thrift store like I did!