Is upgrading this card necessary?

Hi, I'm going to be purchasing this computer during boxing day sales: http://www.bestbuy.ca/en-CA/produc [...] 59801den02

I have a number of questions:

1) I'm not sure if I should replace the graphics card (AMD Radeon HD 7570), I don't know if it's good enough for the games I want to play. (Cod4, Runescape, Minecraft, League of Legends, and possibly some other FPS games).

2) If I need to replace the card, what do you recommend? I want to be able to play on high settings with a smooth frame rate.

3) Will I need to purchase a power supply for this card? Which?

4) Will I need to ground myself when changing the card? What should I use to ground myself lol?

5) Overall, do you guys think this computer would be good enough for these games after I upgrade the GPU?

Please just let me know if the card will need to be upgraded or not. I'm not looking to run 200 FPS or anything, just around 80.

Edit: I'm going to be using a single-monitor setup, and I think the native resolution of the monitor I'm getting is 1600 x 900