I would like to buy a graphics card, but not sure which one to buy.
I dont know which graphics card are supported to my computer.
Need your advice.
For more information see the attachments.

ADMIN-PC.txt : computer details

[recovering disk space, attachment deleted by admin]You'll need a PCI-E graphics card.
What power supply do you have?  (Make & model)
What's the intended purpose of the card, is it for gaming?
What's your BUDGET?I am INTERESTED in this xfx nvidia gt n 640 4gb ddr3 graphics card.

http://www.flipkart.com/xfx-nvidia-gt-n-640-4-gb-ddr3-graphics-card/p/itmdhkpzuznk23c7?pid=GRCDHKPNQAYMYZZC&cmpid=content_graphics-card_8965229628_gmc_dyn&tgi=sem,1,G,9226359,d,,content,19238968460,none,,,c,,,www.game-debate.com,boomuserlist%3A%3A2582420,,,&gclid=CNrlgJianboCFeYA4godRSMAUgThat's compatible, assuming you have a decent power supply.  It's not a particularly powerful card for gaming though if that's your aim.
Also, don't buy the 4GB version, it's more expensive than the 1GB or 2GB variants and it's no faster.  There are several different variants of the GT 640, the one with GDDR5 memory is faster than the models using GDDR3.  There's also a GT 640 v2 card which should be faster than the original variant due to higher clock speeds and a new core.

Edit: looking through what's AVAILABLE on your link, the GTX 650 and 7770 are available for a similar price and perform better, or there are standard GT 640s available a fair bit cheaper than the 4GB GT 640.Tell me any one of similar price and ram but of better performance?These ones would be much better (Better GPUs, Faster memory and cost less) - http://www.flipkart.com/zotac-nvidia-geforce-gtx650-1gb-1-gb-gddr5-graphics-card/p/itmddmmkaqx7gjhh?pid=GRCDDMMGUVQFVWMZ&ref=2158a5b3-5402-4ac0-aff5-af04ac98c253 and http://www.flipkart.com/gainward-nvidia-geforce-gtx-650-1-gb-gddr5-graphics-card/p/itmdgszzzq3c5gyg?pid=GRCDGSZADXKZ59WT&ref=e7f0cfc8-d438-483d-b1d9-5e84b9e74cd5

It has 1gb memory, however as Calum said, 4gb of video RAM gives no performance increase in almost all cases.  The only reason you GET mid-range cards with 4gb memory is because it makes the card look a lot better than it is so it can be sold for more where the actual cost to the manufacturer of adding the extra RAM is very low.The Zotac card is the one I had in mind, thanks for the link Cameron.
Bear in mind the GTX 650 does need a 6 pin PCI-E connector though, hence why I asked about your PSU in the first post.How to know the powersupply, I have checked the PSU no sticker found.
While i was searching my computer papers, i got this (see attachment), if this is PSU then, can 200 watts work??

[recovering disk space, attachment deleted by admin]That's not going to work well with any additional graphics card, and almost certainly won't have the right connector for a midrange card like the GTX650, unfortunately.Then what about changing the PSU???
That would be advisable if you want to upgrade the graphics card, yes.I have a question if i replace that 200 watt PSU with a 400 watt PSU with no graphics card installed, just only replacing the PSU. Does that effect my computer?

secondly, what type of PSU should i take for that graphics card?It won't affect your PC, no.  A higher wattage power supply doesn't draw that wattage all the time - just the wattage your PC needs.  So, if your PC currently DRAWS, say, 150W, and you replaced your 200W PSU with a 1200W PSU, it would still only draw 150W (possibly slightly higher depending on efficiency).
I would get at least a quality 450W PSU.That helped me a lot to understand my electrical engineering.

So, I need 450W PSU + ZOTAC NVIDIA GeForce GTX650 1GB 1 GB GDDR5 Graphics Card .


1 more question, You can see my computer details from the text attachment, in that, you can see that i have a internal graphic memory of 1310MB. So, my question is after adding this graphics card how this card help me or improve my performance.

Ok that graphic memory is not there in the text, but i have a graphic memory of 1310MB.