Help with $700 budget gaming PC, already have GPU and PSU

I'm planning on building a new computer system to replace my 5 years old desktop. I'm currently using my laptop for gaming at university, and sadly it only has Intel GMA 950 so I wanted a PC more suited for gaming  
I live in Canada so the budget is in Canadian dollar. I have not kept up with the computer hardware news for several years so I'm kind of lost to which system gives the best price/performance.

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APPROXIMATE PURCHASE DATE: Within 2 weeks

BUDGET RANGE: $700 Canadian

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: Gaming, surfing the internet, and movies

PARTS NOT REQUIRED: OS, speaker, GPU and PSU

PREFERRED WEBSITE(S) FOR PARTS: ncix.com, newegg.ca

PARTS PREFERENCES: No perference, just which ever parts will give me the most bang for the buck

OVERCLOCKING: Moderate OC, will be OCing but not pushing it to its limit

SLI OR CROSSFIRE: Possibly

MONITOR RESOLUTION: 1440x900, 1600x1200, 1680x1050 any one of these 3 resolution is good

ADDITIONAL COMMENTS: Currently I already have Radeon 4770 and Corsair 750W PSU. I know the PSU sounds like it might be overkill but I plan on re-using it down the road for new builds with multi GPU. I bought those two on the spur since they were on a good deal. I have Vista 64-bit so OS is not a problem, but I'm looking for monitor, keyboard and mouse within that budget as well. I'm looking for a monitor that gives one of the three resolution I listed above. I'm willing to go over budget by a small amount if its reasonable enough. Thanks for your help guys.