How important is the graphics card for photo editing?

Hi all
I just bought a new pc:

Intel quad core i5 3450 3.1 GHz socket 1155 Ivy Bridge
mobo AsRock H77 PRO4/MVP
psu XFX Pro 550W
8gb ram Corsair Vengeance LP
HD WesternDigital Caviar Blue 500gb
Samsung DVD
windows 7 home premium 64 bit

Monitor: Dell U2412M 24' 16:10 1920x1200px

Now I'm using the integrated graphic card (Intel HD2500) but with this card there are some problems with digital signal (I don't see anything after booting, it's a bug of this video card: http://communities.intel.com/thread/29246?start=0&tstart=0 )

so I just bought an economic dedicated video card: Sapphire Radeon HD6450 http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=917&pid=316&psn=&lid=1#

I bought this card because I haven't much money, I hope this card it's good for photo editig. What do you think? My dilemma: how important is the graphics card for photo editing? I don't use my pc for gaming, only for internet and photo editing (= photoshop cs6)

Thanks in advance for your replies, I hope I can clarify this