Plus, if you ever decide to get a little more juice out of your 945, it'll have some decent OC muscle to help you out. Otherwise, spring for the Gigabyte 790GX posted above if you want the option for Crossfire in the future.
For a GPU, at your resolution, either a Radeon 4770 or 4850 will be great. Chances are, you can pick up a 4850 for a better price than a 4770! Simply find one that suits your needs in terms of cooling/rebates.
As for RAM, the Mushkin sticks the poster above linked to are a great deal if you take advantage of the rebate.