The best thing to do wipe the new computer and put a fresh install of Windows onto it
You can do the same with your current computer to clean it up.
You can also buy a cheap prebuilt and a copy of windows and do the initial install yourself. That way you avoid all the extra crap.
Whatever you decide to do, I would highly recommend that you pick up some good backup software like Acronis and do a full backup of your newly installed clean system. That way, at some point in the future when crap messes up your system, you can simply back up your data, do a restore from the clean image to bring your computer back to a healthy state.
