Appropriate Graphics Card

I want to add some more info: My monitor is Dell 22" LCD TFT, whose max. resolution is 1680x1050. I will use 450 Watt PSU. My budget for grapgics card is below $100

For video editing get HD5570 and for a motherboard maybe http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Very in-depth article about workstation cards and addresses using a gaming card instead.
http://www.xbitlabs.com/articles/video/display/quadrofx...

Given the price point you're working with, the only card you can afford is the weak firepro 3700. You could look at something like this since the actual hardware is the same:
http://www.techarp.com/showarticle.aspx?artno=539&pgno=...

I'd suggest though forgoing the GPU and spend the extra money on an i7 8xx CPU instead and get any GPU that will fit the budget. The HT of the i7 will probably make more of a difference than any help a sub $100 GPU could. And most GPUs are supported by CS4 and 5. List of supported is linked in table of contents.
http://kb2.adobe.com/cps/404/kb404898.html

You could also look at the AMD 1055T and an 890GX mobo for the same cost and save the money for the GPU.

Actually, I had never have to use Graphic card as previous intel or amd boards had ob-board graphics. Only because intel's new processors are such that they require a separate GPU, I am bound to use one. So I do not like to spend much on this. Only that much which would help me doing my jobs smoothly. Presently, my choice is i5-750, but I can choose i7-860 if it gives me mileage for the extra bucks I shall spend. I have another question in choosing a Gr.Card. ATI or nVidia, which one is better. Can any one throw some light on this?

The i5-750 is fine and one of the best processors for the money. The i7 is, of course, better but the cost isn't in line with the benefit I would say.
If you aren't gaming then something like the HD5570 rolli mentioned would be a fine choice but if you were happy with onboard graphics before then an HD5450 should be more than enough and save you some money.

Here's the benches for CS4. Looks like the i7 has about a 11% lead on the i5. Both beat the AMD 1090, so forget that idea. Whether 11% is worth a 50% price increase is up to you.
http://www.anandtech.com/bench/CPU/25

If integrated graphics are enough for you, spend as little as you can for one on the supported list. Might give a little bump in performance and keep it cheap.

Best answer selected by rangpuriya.

Thanks to all forum members who responded quickly and helped immensely in the process of my selection of an appropriate Gfx card. I'll select one between HD 4650 and HD 5570, for sure. Hope I'll get your help in the future also. Thanks again!

Keith, there are many varieties of xfx radeon 4650 grafix card. Broadly, 2 varieties - mem size 512 mb and 1 gb. There are memory interface bus - 64 bit and 128 bit; memory clock - 800 mhz and 1000 mhz. Please tell me specifically which one you chose for yourself among these flavours.

There's a link to the specific graphic card I picked in the "Selecting the Components" post. I only see two PCI Express XFX RADEON 4650 cards on NewEgg: 512MB and 1GB RAM (I picked the 1 GB version). Keith