The advice from Microsoft here will cost you money whether you pay for a new version of Windows or have to buy a new computer and the chances are your computer in it's current state won't be powerful enough to run a new version of Windows. Your computer running XP may still be in good shape and running fine. There is another way, your computer may not be powerful enough to run the latest Windows OS but it can still run an up to date system in the form of Linux. Fuller Computing Services Ltd supports Ubuntu for desktop and Ubuntu for business. Ubuntu is a modern desktop OS that can run effortlessly on older hardware that can't support Windows 8, it is also a much cheaper option than buying a new version of Windows or even a whole new computer.
If you do decide that you want to buy an new computer you may want to consider a ChromeBook. ChromeBooks are cheaper than Laptops running Windows, they are faster, secure and have a longer battery life than their Windows counterparts.