Which Graphics card for dual monitor?

Hi there,

I'm planning on starting music production using the software FL studio. I intend to have a midi keyboard connected, some speakers, and possibly some effects units down the road, who knows. I also want 2 displays, which I have at the moment, being 24" monitors.

The pc which I plan on getting has the basic specs of:

AMD FX-4100 Quad core processor - Overclocked to 4ghz per core.
16GB of 1333mhz RAM DDR3
1TB HDD
Windows 7 64 bit.

My concern is in regards to the GPU. I can either get a ATI radeon HD 6450 1GB card or for a little bit more a ATI Radeon HD 6670 2GB card.

My question is which graphics card would be best providing I want 2 x 24" monitors running? Would the 6450 be fine or should I pay a little more and get the 6670.

Also, I will be doing no gaming, just music production. - semi intensive applications