I am looking at buying an HP G62t with these specs:

i3-370m
4gb (1DIMM)..easier to upgrade to 8GB
250GB HDD blah blah blah

My question is about the GPU

When customizing this laptop on the HP site, I am given the choice between Intel HD graphics(pretty crappy), 512MB ATI Mobility Radeon HD 5470 Graphics, or 1GB ATI Mobility Radeon HD 5470 Graphics.

I am confused because I thought that the HD 5470 was an integrated unit.
By the way, I am a casual gamer, this laptop will mostly be used for Office software, photoshop and programming, with some mildly-tasking gaming. (Left4Dead2 etc.)

So if anybody can clear this GPU issue up for me that'd be great, Thanks.