4. While the Samsung Ecogreen F4 is a good choice - I do not recommend going with a 5400 RPM drive as your primary - that will be a massive bottleneck. Get a 7200 RPM drive or get an SSD as your primary.
In a few months, you should plan then I say this because Nvidia will introduce their 6xx GPUs and in the next few weeks AMD releases the 7850 and 7870. Also Piledriver will come out of the CPU lineup as well as Ivy Bridge from Intel.