Changing video cards?

[DZA]

I have a brand new Imac 24 with a
Chipset Model: NVIDIA GeForce 7300 GT
Type: Display
Bus: PCIe
VRAM (Total): 128 MB
Vendor: NVIDIA (0x10de)
Device ID: 0x0395
Revision ID: 0x00a1
ROM Revision: 3022

Am i able to add the 256 card after purchase?

 

[D3v1L80Y]

No, if you want the 256 you need to get it at the time of your order.
You cannot upgrade the graphics in iMacs.