What do you mean "buying a shield"?
yes, the GTX750ti is a fair amount better than your current graphics card.
But, I always think one should buy a significant jump in capability or risk being disappointed.
In this case perhaps to GTX760 or even GTX770 levels.
How big a jump you can manage is limited by your psu and budget.
What is your psu, and what is your budget?
MY budget for a card is around 200, i guess I could go over it, but would it even be worth it? My psu can be changed. im getting a new case and motherboard so I may want to change it. it says 240 v on it though (i meant the shield handheld)