Sapphire AMD/ATI Radeon HD 6770 vs Radeon HD 6870

[romi1208]

HELLO!
I'm new to this forum and actually new to the world of modern gaming so please go easy on me.

I was wondering what graphic card to get.I'm really divided between two cards.
Should I get
.
*2GB* Radeon HD 6770 or
*1GB* Radeon HD 6870

Here are some other details
My PC Resolution is 1440*900

Processor - Intel i5 2500k 3.7 ghz
RAM - G.Skill RipjawsX DDR3 8 GB
Motherboard - Gigabyte Z68 Series Motherboard
HDD - Seagate Barracuda 1 TB HDD

Also can you suggest me a good PSU and Cabinet for this configuration. I'm a total PC noob and really have no clue as to what would be the perfect choice (cause there are just so many out there)

 

[panwala95]

where are you from because here in india cabinets (good ones) are difficult to find
i would take the hd 6870 1gb edition anyday

 

[romi1208]

where are you from because here in india cabinets (good ones) are difficult to find
i would take the hd 6870 1gb edition anyday

I'm from India, Mumbai to be precise

 

[panwala95]

then go to lamington road and get adecent cooler master 335 or 430 best you can get in india or go for cheapo zebronics or iball cabbys ..LOLz