If you're going with an Antec PSU the EarthWatts 650W is a very solid PSU with a bit more power than the 520W listed. Plenty to power an i7 build with one or two graphics cards.
I say go for that power supply, the Antec Neo Eco 520W and since you are on a budget you can get this video card, even tough it doesn't have DX11, but still a very decent card.
If your build is for gaming the graphics card is the single most important part of it, don't cut your graphics card, cut anywhere but your graphics card. Get at least a 58xx series, a 5850 would be good choice for a budget.
If your build is for gaming the graphics card is the single most important part of it, don't cut your graphics card, cut anywhere but your graphics card. Get at least a 58xx series, a 5850 would be good choice for a budget.