Unless you are doing some heavy computing, desktops are so 90s. VerY few of them sold any more. Laptops and tablets are far more handy for the average household. I can do everything on my tablet except graphic design and heavy duty word processing. Neither of which I no longer do. Heck my tablet generally sits unused 95% of the time. I use it for picture transfer and to back up to my external hard drive and thats about all.
If your looking to upgrade, think long and hard about what you need and how you use it before spending dollars on anything.