Need Help! Upgrading PC (a bit skint)

[Morrissey]

I'm absolutely clueless about these things, I need your help.
I'm looking to play pro evo 2014, dota 2, and possibly nba 2k14.

Here are the system requirements from canyourunit:

http://picpaste.com/pics/970yPFlu.1393128701.jpg
http://picpaste.com/pics/xURti8f6.1393128894.jpg

Soz, it won't embed.


Is my video card the only thing that needs upgrading?
And if I only upgrade the video card, will the game be sluggish because my processor barely meets the minimum req?

Thanks.