Go with the Antec performance, you'll benefit from having a 500W PSU with a more powerful card. Also, could you provide a link to it, so we could see if the ampage on the 12+ volt rail is good enough?
For the graphics card, I'd go with either this card:
or, if you can afford it, this one:
Don't go with a Radeon X800, they suck compared to the Nvidia equivalent in price.
Also, you may want to upgrade the amount of ram to 2 gigs, as games such as FEAR and Battlefield 2 will benefit from the extra amount. And you say you'll be overclocking the processor? If so, you might want to buy more expensive performance ram.
Anyway, good luck with your first build