HELP WITH BUDGET GAMING PC? 700$

For the budget and how much you're willing to stretch you could do so much better.
Check out my $650 build here:
http://www.squidoo.com/electronicandmore
Swap the i5 3450 for the i5 2500K (+10)
http://us.ncix.com/products/?sku=57962&vpn=BX80623I52500K&manufacture=Intel&promoid=1027
Swap the motherboard for this one (+45)
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157271
Swap the 6870 for this 7850 (+90)
http://www.amazon.com/Sapphire-Radeon-PCI-Express-Graphics-11200-01-20G/dp/B007JCNOZA%3FSubscriptionId%3D19BAZMZQFZJ6G2QYGCG2%26tag%3Dsquid1240995-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3DB007JCNOZA
Swap the PSU for this CX600 (+3)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139028
Total: $800 before rebates.

The 7850 will give you way more performance and the Asrock Extreme3 Gen3 Z68 will give you 8x/8x if you plan to Crossfire/SLI in the future. The CX600 will be able to supply enough power for Crossfire 7850. The 7850 can overclock to the performance of a GTX 580 easy as many reviews point out. Also the power requirements for it are so little the CX600 will be able to handle 2x7850+i5 2500K overclocked.

With the current Z77 board you have, you won't get PCI 3.0 anyways since SB doesn't support it, you might as well get a cheaper board that still supports PCI 3.0 if you end up upgrading to Ivy Bridge but also supports 8x/8x.