@Latrobe, look at
my post a couple of pages back and Bino's answer and the comments to both and you'd surely find an idea about what components you'd get for $700 or less.
@wpeters, I'd rather read posts about people asking before buying if a certain computer would fulfil their needs than answering why their "brand new" ultra low budget "grammy goes banking" laptop doesn't produce a crispy live-like image with full eye candy settings. The idiot is the one who buys before asking.
One hint: If it says "Intel -- Graphics", forget about it or prepare for buying both a video card and a power supply, adding another $200 or more to the price. I see you already have a post in the AH Classifieds forum for multiple mid range gaming rigs. Is this about the same project or do you have another going on for one for yourself? In the latter case, another thread there might help.