Educate me on laptop choice

RAM does not trump the CPU, but you do need enough of it for the laptop to work efficiently. 4GB is generally enough for the average person and 8GB should be more than enough for the average person. There are some laptops with 6GB of RAM.

The basic thing you need to know about CPUs are:

1) Intel CPUs can process more instructions / data per every 1Hz than AMD CPUs can so at the same clockspeed Intel CPUs have roughly 15% - 20% more processing power.

2) Having more than 2 cores can come in handy, but they are only a benefit if the program you use have been designed to make use of more than 2 core. The vast majority of programs are designed to use up to 2 cores.

3) Double the cores do not mean double the performance. A car with a 200 HP engine will not go 2x faster than a car with only a 100 HP engine. If programs have been designed to use more than 2 cores, then the improvement could be anywhere from 10% - 40% depending on how well the programs have been designed to use more than 2 cores (if at all).

4) Hyper Threading (HT) only applies to Intel CPU which have that capability. Similar to multiple cores, the program must be designed to use HT, most programs that people do not make use of HT. The exception would be some video editing / encoding programs and most likely PhotoShop (not certain). These are virtual cores, not physical cores so while it can boost performance, having actual physical cores is generally better.

5) Forget able overclocking on a laptop.

Windows 8 is a new so there may be some compatibility issues with some older / recent programs that you may use. I prefer Win 7 if possible. At least Win 8 allows you to use a touch screen if that is something which appeals to you.

The Samsung Series 3 NP300E5C-A0BUS is not a bad laptop. Very basic and inexpensive. The Pentium G950 should be enough for all your basic needs.

The Lenovo® IdeaPad Z580 (59350984) is more expensive because it has a more powerful dual core i5 CPU. This should last you for several years as long as you needed remains basic enough. The integrated Intel HD 4000 graphic core is good enough to play some non graphically intensive games with medium graphic settings should the need arise. More than enough to watch HD movies. The 6GB of RAM can be helpful when editing large image files in Photoshop.

The Asus X53E-RS51 uses an older 2nd generation "Sandy Bridge" Core i5 CPU compared to the 3rd gen "Ivy Bridge" CPU in the Lenovo. Nevertheless, the CPU is still considered powerful. It has the older Intel HD 3000 graphics core. The newer Intel HD 4000 is about 30% - 40% more powerful (better for games), but the Intel HD 3000 is more than enough for basic needs like watching HD movies. I have read that customer support is somewhat lacking compared to Lenovo though, but it varies from person to person.

Toshiba Satellite L855D-S5242 has the AMD A8-4500m CPU. More than enough for your needs. Being a quad core CPU, the A8 CPU can be as fast or faster at certain task than the Lenovo with the 3rd Gen Ivy Bridge Core i5 CPU. It matches the Lenovo's 6GB of RAM. The integrated graphics core (Radeon HD 7640g ???) is a little more powerful than the Intel HD 4000. It costs less than the Lenovo and weighs a little less too I think.

Overall, it boils down to the Lenovo or the Toshiba if it were my decision. I would probably go with Toshiba. It's less expensive and the performance difference compared to the Lenovo will not really be noticeable. I think Photoshop can make use of quad cores and so can video editing / encoding programs.

Lenovo for sure, especially since it has USB3 ports so you can easily attach external storage, when you start needing it

But 720p on a 15 inch screen sigh...yes it's $500 but common it's 2013. Industry needs to squeeze in more pixels.