PCPartPicker part list:
http://pcpartpicker.com/p/3n0zU
Price breakdown by merchant: http://pcpartpicker.com/p/3n0zU/by_merchant/
Benchmarks: http://pcpartpicker.com/p/3n0zU/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($109.99 @ Amazon)
Motherboard: ASRock 970 Extreme3 R2.0 ATX AM3+ Motherboard ($58.00 @ Newegg)
Memory: Mushkin Essentials 8GB (2 x 4GB) DDR3-1333 Memory ($76.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($75.79 @ Amazon)
Video Card: MSI GeForce GTX 750 1GB Video Card ($129.98 @ SuperBiiz)
Case: Rosewill REDBONE ATX Mid Tower Case ($39.99 @ Amazon)
Power Supply: Corsair CX 500W 80+ Bronze Certified Semi-Modular ATX Power Supply ($34.99 @ Newegg)
Monitor: Dell E1914H 18.5" Monitor ($79.99 @ Micro Center)
Total: $605.72
(Prices include shipping, taxes, and discounts when available.)
This is what I would build. This build gives you more room for improvement MAs the PSU ha significantly more watts. As an added bonus, its modular so you don't have cables all jumbled up inside your system.
To buy a new monitor, your going to really restrict what you can do with this build. I would suggest buying a refurb off of eBay
http://www.ebay.ca/sch/Monitors-Projectors-Accs-/162497/m.html?_ssn=dell-official-store-ca-refurbished&_sop=15 its a Canada based link, but if you can find another Dell overstock store or something like it, then order from there.