Dual monitor requirements

I'm thinking of running dual monitors on a new build with an amd 720, 4 gb of gskill, and a 4870. The monitor I have now is a 5year old 19" acer I believe (in iraq, can't check) runs at lower resolutions. My question is: what components (ie gpu, psu, etc.) do I need to consider for the kind of multitasking I'm considering. This would include watching tv while surfing web, playing total war, encoding, and other general use. My budget is around 800-1000 US, but it's flexible. Should I be looking at a quad core, possibly an I7, or maybe crossfire or an x2 4870?

You might want to consider a quad core CPU, like the AMD X4 955 Proximon listed or a Core i7. But you'd need a good powerful PSU for this, which one do you have now

If you overclock the CPU you'll do pretty well. I get excellent FPS in large battles with my 4670, but then I have an overclocked E8400. If you were to get a 720 up around 3.4GHZ you would probably see the same.

There would be a frame drop with a second monitor. Crossfire wouldn't be the solution, but a second card would. Run each separately. Assign the TV tuner to the 3rd or 4th core, and you should be good.

I said 4670 up above but meant 4870... I have a Sapphire Toxic 512MB 4870 and it plays Total War well... although I got tired of the campaign game. Too long.

The 750TX is all the power you need for two 4870s. The 850TX is a slightly higher quality PSU, but it's not a big deal. About a 20 dollar difference

Sure, that will be fine. 4850s will perform better of course.