Upgrading my graphics card

[Optimus GriimE]

Hi i recently purchased a new computer and today brought bioshock 2, my system struggles to run it with the graphics on medium, i was very confused by this until i checked bioshock2's system requirements, my cpu and ram are more than capable however my graphics came out at 25%(ran a check on bioshocks website) the card i am using at the minute is the ATI Radeon hd 4350, so i just wondering what card you guys would recommend i should get, it will preferably have to be lower than £100, thanks.

CPU: Quad core processor @ 2.5ghz
RAM: 6GB DDR2

 

[Fat.Clown]

usually pre-builts like yours come with wimpy power supply and cannot handle stronger graphics card.

if above statement holds true in your case:
XFX HD 5750 512MB Dual DVI HDMI Display Port Out PCI-E Graphics Card
Be Quiet Straight Power E7CM 480W Modular PSU

if not,
HIS HD 5770 1GB GDDR5l DVI HDMI Display Port Out PCI-E Graphics Card

edit: oh.. you lowered your budget
let me look around more then

 

[Optimus GriimE]

Yeh sorry about that, i just thought 150 is abit too much right now, and yeh it is a pre built, its an acer aspire m3802

 

[Fat.Clown]

that acer comes with a 250W power supply
Sapphire HD 4670 512MB GDDR3 DVI VGA HDMI PCI-E Graphics Card
with
Corsair 400W CX PSU - 12cm Fan 80Plus Certified Efficiency 6x SATA 1x PCI-E
or
Antec 380W EarthWatts Green PSU - 80plus Bronze Certified
the antec does not come with a power cable, but you can re-use the one your have currently
both are solid units, the Antec is a bit cheaper, but the Corsair is quieter (I own both of them )

edit: if you want to go over budget a little bit, the HD 5670 is faster and have DX11 support

 

[Optimus GriimE]

Now i wish i had taken some more time and got my bro to build my own

 

[Fat.Clown]

even though the core 2 quad is 1 generation behind current, but I think a quad core and 6gb of ram is still a force to be reckoned with

maybe it's because I am on the core 2 quad myself hahaha

 

[Optimus GriimE]

Now i feel **** as i really should of taken more time but seeing as tho i have it and there is no going back, what would you recommend to get the very best out of my unit?

 

[Fat.Clown]

I'd just go with whatever makes your wallet happy

I use a graphics card similar to the HD 4670 (Geforce 8800GS)
but I can see that it is starting to struggle a bit with the newer games

so I'd pick that HD 5670 if I was upgrading, and then I like my pc to be quiet
so I'd pick the Corsair 400CX

in any case, both the HD 4670 and HD 5670 will be significantly better than the HD 4350