Most video cards will output to 2 monitors, even if it has 3 outputs.
True for most older cards. Any ATI/AMD card that supports Eyefinity (listed below) can use 3 monitors if it has 3 outputs. In fact, they claim that they can actually support up to 6 screens per GPU.
AMD Radeon™ HD 6870 GPUs
AMD Radeon™ HD 6850 GPUs
ATI Radeon™ HD 5970 GPUs
ATI Radeon™ HD 5800 Series GPUs
ATI Radeon™ HD 5700 Series GPUs
ATI Radeon™ HD 5670 GPUs
ATI Radeon™ HD 5500 Series GPUs
ATI Radeon™ HD 5450 GPUs
ATI Mobility Radeon™ HD 5400 Series or higher GPUs
*From the Eyefinity FAQ, link below
Can you explain what needs to be displayed on the 2 monitors and the TV. I was thinking that if the TV is to display what is on one of the monitors then a VGA splitter or if the TV doesn't have HDMI or VGA input then a VGA to composite adapter after the splitter would be needed.
As was already mentioned, 300 watts just isn't going to cut it I think. Depends on the demands that your system already makes and the demands the card makes if you put in a new one. You might want 500 watts, but not sure if you'll find that powerful of a power supply to fit in a mini-tower, it depends on what kind of space it has to fit one.
With an ATI card that supports the Eyefinity feature, which allows for displaying on at least 3 different monitors with 3 individual instances of desktops from a SINGLE video card.
Check out this link:
http://www.amd.com/us/products/technologies/amd-eyefinity-technology/how-to/Pages/set-up.aspxChoose the options you need (for you, I would most likely choose "Productivity", "Advanced", and 3 monitors), then click the "See Recommendation" button. On the next screen, it will suggest some example chipsets (for the options I've suggested, it came back with ATI Radeon 5570 or 5670). You may choose other options if you feel what I suggested isn't right for you. I'm just guessing.
You also need to pay particular attention to the "AMD Eyefinity Technology Support Information" section. There are 3 ports the card will need:
1. AT LEAST ONE Display Port or Mini-Display Port (to which an active Display Port adapter can be attached).
2. AT LEAST TWO of the following: HDMI, VGA, or DVI. (Any combination will work for this.)
I would suggest getting an adapter for the Display Port and two ports that all match whatever connections your screens can support. Different models of cards will come with different ports, so you'll have to do some hunting for the one that's right for you. If you can't find a perfect match, I'd suggest getting one with the Display Port and either DVI or HDMI ports. Even if all the ports aren't right, you can connect the ones that are right and get an adapter for the others so the will be right. I don't suggest getting one with VGA unless the screens have VGA. Sometimes VGA doesn't always give desired results when adapting to HDMI or DVI, but adapting DVI to HDMI or vice versa usually works fine. Going from HDMI ports to a VGA monitor usually works fine though.
***Please note that just because the model is listed as supporting Eyefinity, it MUST have those three ports (Display Port and two normal ports). This will depend on individual card manufacturers' models of those chipsets.***
I hope that wasn't all too much at once. If you're confused or have any questions, please ask and I will try to clarify.
Other Eyefinity pages you might want to look at:
Eyefinity FAQ
http://www.amd.com/us/products/technologies/amd-eyefinity-technology/how-to/Pages/faqs.aspxEyefinity How-to
http://www.amd.com/US/PRODUCTS/TECHNOLOGIES/AMD-EYEFINITY-TECHNOLOGY/HOW-TO/Pages/how-to.aspxI don't think the following will work for you, but I would like to mention it:
Another option is getting two identical cards and linking them (SLI for Nvidia cards, CrossfireX for ATI/AMD cards). From what I've read, all the ports on the cards should be able to display individually. The downside to this method: twice the heat (two cards instead of one) and a bit expensive. Plus, you will definitely need a more powerful power supply than 300 for this. Something in the neighborhood of 600+ watts most likely. I haven't looked at the full specs on your system yet, but you would also need two PCI Express x16 slots as well.