What amount of RAM and processor speed do I need?

I'm going to buy a new computer soon, because the one I have is getting a bit old and not running as well as it used to. I'm a bit unsure of how much RAM and prosessor speed I'll need, though. I mostly use my computer for web browsing and playing The Sims 3 with four expansion packs and two stuff packs. I also do occasional work on Google Docs. There's also a website that I use quite often, Tumblr, but I've always had to use it on my iPhone because my current computer with 6 GB RAM and a 1.70 Ghz processor was never able to handle the website.
Thanks you in advance for any advice.

Added (1). I'm looking to spend around $500. Money is a little tight right now, so I won't be able to afford something super expensive.

Added (2). I'm interested in a desktop.

8 GB would be a good amount for RAM

What speed of CPU to get depends on your budget and the type of CPU, as well as what you are using it for. Keep in mind that the performance of games is affected most by the video card GPU.
Are you getting a desktop or a laptop?

In general, an Intel i3 or i5 processor, or an AMD A8 (laptop) or AMD FX or higher end Phenom x4 series processor would be desirable.
http://www.tomshardware.com/reviews/gaming-cpu-review-overclock, 3106-5.html

Not a Pentium, Core2Duo, Celeron. Sempron. Athlon, E-350 series or other budget CPU like that

If you really want performance, go for an Intel i5 with atleast 2.5Ghz and Nvidia 540M GT. Ofcourse, the higher the better. Atleast 4GB of RAM. 8GB of RAM is also good, but I find no point in taking it unless you are really into multitasking and doing some coding which is for multimedia people.

Make sure that what you're going to buy quite a good cooling system since laptops are very prone to overheating. There's a thermal control for Intel which slows down your laptop when the CPU gets hot and it makes your processor slow for a small amount of time and gets back to normal. It can be fought with throttlestop to prevent that, but there's a little risk if you don't know what to do with it.

Memory ram has nothing to do to what you mentioned of the website.a good processor with 2 gb ram it is good for multitasking, nevertheless today all computers are 64bit that's why most of them have 4gb ram installed.
You sad 1.70 Ghz processor but didn't mention which processor. Which i think is damaged since it can handle a simple website.

Intel i3 0r a quad AMD processor will do it. The Sims can be played in a integrated video card.
Either one will come with a minimum of 4gb ram.