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.

=============================================================================

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.

It ended up being close to $800, sorry about that. It was really difficult to push it as hard as I could without jumping over the price a little. You can always cut back or change things if you want to. Just dont change the Motherboard (because it is crossfire) and processor (unless you know what you're doing)

Case: http://www.newegg.ca/Product/Produ [...] 6811146047
This may be one of the more overpriced parts of the whole thing, so it would be a good place to cut back on, but it's really solid.

Keyboard: http://www.newegg.ca/Product/Produ [...] 6823175103
It's an amazing keyboard, but you may be able to find one you like for cheaper

CPU: http://www.newegg.ca/Product/Produ [...] 6819103678
I tried to get a decently high-clocked dual core, and this will be more than enough to run games

DVD/CD drive: http://www.newegg.ca/Product/Produ [...] 6827151171
It's solid and fairly cheap

Monitor: http://www.newegg.ca/Product/Produ [...] 6824236056
This is one of the more expensive parts, but its 1680x1060 and a really good monitor

Hard Drive: http://www.newegg.ca/Product/Produ [...] 6822148395
Same one I have, really good for the price and runs really well

Mouse: http://www.newegg.ca/Product/Produ [...] 6826104076
While you may think this is expensive, it's probably the best gaming mouse, and especially for $50

Mobo: http://www.newegg.ca/Product/Produ [...] 6813130136
It was really hard trying to find a motherboard that would run crossfire at such a low price, and this was the best I can do

RAM: http://www.newegg.ca/Product/Produ [...] 6820231122
You need 4 gig, here it is

The real budget drops to about $550 after adding the monitor, mouse and keyboard.

From here on you have the option of the Intel Core 2 Duo E7400 or the AMD Phenom II X3 720. The best case choice would obviously be the Antec 300 and if you're only doing a slight overclock you won't need a cooler. Ram you should probably stick to 4gb ddr2, and a crossfire enabled mobo in case you want increased fps by adding a second 4770 later on.

dirtmountain hit it straight on the head but switch to this mouse combo and order from Ncix for cheaper shipping. Ncix price match so overall you will get it cheaper than on newegg.

You will also want to pickup a cd drive so that will cost about $20 more.