1. Although you may prefer XP to Vista, it is probable that you are simply
more familiar with it. If you would give yourself some time to become
accustomed to Vista, you might find that you like it. I know I do.
2. You can't literally "uninstall" Vista, but if you want XP instead, you
simply do a clean installation of XP the normal way. That will format the
drive, removing whatever is on it.
3. Do you already have a copy of XP you want to install? Did it come with
your old computer? If so you need to be aware that OEM versions (such as
those that came preinstalled on computers) are permanently tied by their
license to the first computer they are installed on. If that's your
situation, your copy of XP is not available to be used on your new laptop.
4. Over and above the licensing issue in point 3, many OEM version of
Windows XP are BIOS-locked to the computer they came with, and you actually
won't be able to install it on a different one.
5. You should check with your vendor to be sure, but the warranty on your
new computer may be voided if you change operating systems.
6. Laptops often have special drivers they need for components within them.
Your new laptop undoubtedly came with all the drivers needed for Vista, but
it didn't come with the drivers needed for Windows XP. Finding and getting
the drivers you need may be a problem.
If I were in your shoes, I'd stick with Vista.
If you still want to uninstall:
The normal way to "uninstall" any operating system is to format
the hard drive and install a new OS of your choice.
After backing up any data you wish to transfer to the new OS
installation, simply boot from the WinXP Home installation CD. You'll
be offered the opportunity to delete, create, and format partitions as
part of the installation process. (You may need to re-arrange the order
of boot devices in the PC's BIOS to boot from the CD.)
HOW TO Install Windows XP
Then the backed up data can be restored and applications re-installed.
You can even try a dual boot, where you have both Vista and XP on the same system. Click HERE
for pictorial guide.