Your best option to replace XP - if you are worried about security or viruses (and being expensive forced to buy anti-viruses internet security software yearly), and a company trying to bully you even couple years to upgrade their software, or a computer that does not last is to buy a MAC.
Bought my Mac Pro desktop in 2006. The only think I ever needed was to add more memory and that is only because of all the bells and whistles that all these interet sites think they need. Sure, I needed to get MS WORD for Mac (only because I am used to it), but it comes with its own Office suite of Safari, Numbers (think Excel) and Keynote. And many of the MAC software is Free on the Internet if you want more, because Apple users believe in shareware.
With MS trying desperately to make a Mac-like computer (and failing big time) I am so glad I did choose to switch. In the long-term its less money going out, less worry about viruses, and far more reliable. Something to think about.