Looking for new GPU for my old PC

[Lukaz]

Greetings. I'm looking for a new GPU to replace my old one cuz it realy old. I have few question please help me :
First this is my PC:
-Intel Dual Core e5400 2,7ghz / 3,24ghz
-mobo : g41m-es2l
-memory 4gigs ddr 2
-Ati Radeon 5550 1gigs DDR3
-550 wat PSU

Yes i know the first think you guys gonna say is "Bottleneck" i dont have money to upgrade all of it so here is my question:

-I'm looking for a GPU around 150$bucks. can you please help me find a good one for my PC
-I already have my eyes on Sapphire HD 7770 Vapor-X OC 1Gb 128Bit DDR5 can the GPU slot fit in my Motherboard slot?
-I'm playing on 1080p res and i'm planning to play new games like The Witcher 2 and Battlefield 3 on high/ultra settings.
-What do you guys think when buy GPU better Big memory but DDR3 or just 1 gigs memory but have GDRR5?

Ok thats my question. Note ultra/high settings in my case is not all option is set to is highest. I'm not going to use anti aliasing and shadows because in my opinion that 2 not going to make a big change ingame and anti aliasing is making many games lagging so i'm going to turn that off.

I can't afford more money than that so please if there is cheaper GPU with more performance than HD 7770 it would be great

 

[Sakkura]

A Radeon HD 7770 does look like a good option. It will struggle with Ultra in games like BF3 though.

As for memory, getting GDDR5 is generally more important than the amount.

 

[alvine]

+1 for 7770 or 7750