Debating on graphics cards for new build..

Trying to spec out my first homebuilt system. My faithful Dell XPS2 laptop finally bit the dust.

I have been using the SBM articles as a guide. I am shooting for something around ~750 before monitor.

As far as graphics cards, what would be better for a rig that will do gaming and some solidworks modeling on a large format display (24-25" monitor)? Running dual SAPPHIRE Radeon HD 4850 512MB 256-bit DDR5 cards in crossfire, or running dual GIGABYTE Radeon HD 4850 1GB 256-bit GDDR3 cards in crossfire?

Or would you suggest something else?

Thanks,

Walker