I want to Cast tabs to Chromecast: Upgrade CPU or whole system?

First: I have to admit, I'm more of a software guy and never have been a hardware techie. I have an old system. I'm not sure of the age, but it has to be over five years old. It started out running Windows XP and I installed Windows 7 Home Edition 64bit back in 2009.

System Specs:

Windows 7 PC 64-bit 3 GB RAM, Intel Pentium 2.79 GHz 2.80GHz (per the System Info page)

I don't know the graphics and sound cards, etc... I am not at home right now.

I would like to be able to cast pages to the new Google Chromecast.

Here are the requirements:

https://support.google.com/chromecas..._topic=3210038

If I got something like this, could I just pop it in on the existing Motherboard?

Would I need a completely new Motherboard?

Should I just upgrade the whole system?

I am trying to save $$$

I don't do anything major on my computer. Word processing, e-mail, surfing, etc... I do photography (not professionally) and use Adobe Lightroom for editing.

Thank you :)

So, I need to throw in something like this:

http://www.microcenter.com/product/4...el_Motherboard

Are there other options? Like maybe an earlier generation CPU??

Also, I never consider minimum specs when dealing with anything. Minimum specs mean you can turn it on, or start the function, but it may not be feasible to use. I'd not dump money into upgrading your system if it is really old....I know it sucks but sometimes you just have to buy new/build new.