Budget Range: $600, $650 at the most. The cheaper then better!
System Usage from Most to Least Important: Gaming, internet browsing/school stuff, movies
Parts Not Required: Keyboard, mouse, monitor, speakers, sound card, operating system*, and HDD**
Preferred Website(s) for Parts: tigerdirect.com, newegg.com, amazon.com are my preffered choices, if you can find a part cheaper somewhere else by all means post it.
Country of Origin: United States
Parts Preferences: Intel Core i5, Nvidia GPU, and an EVGA motherboard that is SLI ready if possible for upgrades to GPU down the road. This would mean the PSU should be able to support the power draw from SLI as well. ATI and AMD are an absolute no. 4GB of RAM (DDR3) is my minimum for RAM, I can live with just this much RAM if it is able to put more money towards other areas. I don't like ATI or AMD, so they are a no go.
Overclocking: Not planning too
SLI or Crossfire: Maybe down the road, so I would like everything to be ready for that,
Monitor Resolution: My current monitor is a 19-inch TV @ 1360x768
Additional Comments: It would be nice if the case could be coolermaster, but that might be too much to ask for. lol.
* Operating system will be Windows 7 Home Premium 64-bit
** I'm going to be re-using my Western Digital Caviar Blue HDD for now, it's done me well so far and is just a month old so I'd rather use that 50-100 for buying a new HDD and put it into something else like the GPU.
I did look for the EVGA P55 FTW motherboard but it's in short supply and the lowest price was $202.
There is a micro-ATX EVGA P55V $95 with $20 rebate with x8/x8 SLI but the NewEgg customer review rating is too low to recommend.
The GTS 450 was the best GPU I could squeeze into your budget but should be outstanding on a 1366x768 monitor.