Updating pre-built desktop

[MistahAcid]

Okay.. so I bought this desktop, and I finally decided that pc gaming was the way to go.
My system specs are
i3 - 3240 CPU 3.40GHz
6GB DDR3
1TB HDD
Win 8
280w PSU

I have a Lenovo H520 case
http://www.lenovo.com/images/gallery/1060x596/lenovo-tower-desktop-h530-front-2.jpg

So here's the thing, I want to be able to play games in high/ultra settings, I know I'll need to upgrade My graphics card and PSU as well.. But which card and PSU do I get, also... will they fit?

 

[mf Red]

Your link is broken. If you're gaming at 1080p go for the GTX760 or R9 270x or the 280x if you can afford it.

 

[MistahAcid]

Sorry fixed the link

 

[mf Red]

I can't tell what GPU is in there, but in the pictures it does look like they have a GPU in there already. Good news is you do have a PCIe slot on the motherboard so any of the GPUs I recommended earlier will work.

 

[MistahAcid]

Sorry to bother but i listed my specs.. is the processor enough for any of those cards?

 

[TriBeard]

Your processor is ok, but not great. It'll run games and won't get in the way too much, but you would see a sizable fps gain from a quad core.

That being said, that power supply isn't going to be anywhere near enough for almost any add in card. Some of the higher end graphics cards take more power than that thing can output all for themselves.