ATI Radeon 4350 with Samsung T220 for improving quality

Yes! The 4350 is a great choice to increase video quality--its exactly what I would have recommended. For 1680 x 1050 you will be fine with a 512mb card.
(It's low power too--so shouldn't strain whatever power supply is in your computer.)

I would buy it from newegg.com to get the best price (best buy+ etc would charge you double the $30 that this card is worth) See below:
http://www.newegg.com/Product/ProductList.aspx?Submit=E...

Just to be certain we arent missing anything-- your computer isn't a slimline or an older model right? If not you are good. If you aren't sure post your system information.

Thanks for replying. The machine I'm talking about is running a Pentium 4 2.66GHz processor with Gigabyte 945GCM-S2L S-series motherboard. I'm not sure about the power supply. Is there a way I can check it?

Do you think this machine can support Radeon HD 4650 or maybe Radeon HD 4670? For now, it seems Radeon HD 4350 is the best one which fulfills my need of watching movies. You think 4650/4670 can offer better video quality than 4350 for movies?

Card:

I think the other cards are probably overkill if you are just looking to watch movies--any discrete graphics card is a massive improvement from what you have. Its not worth spending much on an older computer like this either.

To put thinks in perspective--look at Tom's graphic card hierarchy chart.
http://www.tomshardware.com/reviews/geforce-310-5970,24...
As you see the GMA 950 integrated graphics that you have are at the very bottom--while a 4350 is about midway through the chart. Almost any card you can find would be a big improvement.


Computer:

-The power supply information will be written on the side of it inside your case. I am pretty sure you can run a 4350--but you should look if you wanted to get something more powerful.

-I also looked up the motherboard you gave me and it says you should have a PCI express x16 slot--which should be compatible with most new graphic cards. The ones labeled PCI Express 2.0 x16 are backward compatible.
This one is a great price w/free shipping: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

-For best performance if you are running windows xp you should make certain you have 1+ gb of ram, and if you are running windows vista/7 you should have at least 2+ gb.

Overall though... dont spend any more than you have to on your PC--its getting pretty old and you are better off saving for a new one. I think a $20 graphic card is worth it to make useable a while longer but its not worth it to spend more than you have to at this point. New computers that are vastly more powerful are available for $400-500--so spending a hundred on this one wouldn't be practical.

Just to be clear, any "improvements" you may potentially see will be limited by the monitor itself. If you are looking for blacker blacks, less color shifting at various viewing angles, less color banding (streaking) issues then you will need to upgrade the monitor, not the video card.

Upgrade from integrate to a discrete video card will probably solve some of the issues you are seeing, but not all of them depending on what you mean by "video quality".