more important for multitasking: processor speed or RAM?

[bhome83]

So I really need a solid laptop. I'm looking at this specific one that gets really good ratings on amazon.com

Acer Aspire Timeline AS4810TZ-4508

The only question I have is that it ONLY has a 1.3GHz Intel Pentium Dual-Core SU4100 Processor. I'm noticing that quite a few laptops are coming out with core i3 and the core core i5. Obviously these are faster laptops, ans sacrifices battery life and overall weight for speed, so I am wondering how big of a difference will I notice between a dual core and a core i3 or i5?

I mainly will be using the laptop for heaving internet use, and heavy HD video use. I want to be able to have many tabs of firefox open at once. Right now my computer is so slow that opening more than a couple tabs is too system resource intensive.

I also want the laptop to be somewhat future proof for at least a few years. I want it to be able to run 1080p .mkv files without a hitch. I don't do heavy photoshopping or video editing so I'm leaning towards the acer timeline.

Is 4gb of DDR3 ram more important for multitasking than having a more powerful (ie core i3, core i5 processor?

Thanks guys for all the help.