(Image credit: Tom's Hardware) Your once-great PC is feeling a bit long in the tooth and can no longer handle the games you want to play — we've all been there. It's time for an upgrade, but you're not sure if you need a completely new PC build or if you can make it another couple of years with a few judicious component upgrades. Many users will upgrade their GPU with one of the best graphics cards and leave everything else in place. But would they get more for the money if they spent it all on ...