Advice On Fitting a New Graphic Card On My Current PC

Led zeppelin blues

Distinguished
Mar 8, 2015
187
8
18,595
I know this is a long enquiry so i humbly apologize to you guys in advance

My current pc specs are -
1 - Intel Core 2 Duo CPU E7300 @ 2.66GHz
2 - 4gb ram which i can upgrade to 6gb
3 - and my current GPU is NVIDIA GeForce 9500 GT
4 - I can upgrade to windows 7 64 bit from 32 bit

Now i want a decent low cost gpu that will play all these new games smoothly atleast on low setting ,im not looking to get high graphics out of the gpu and naturally the 9500gt is a ancient relic now.

so what i was thinking was getting one from these
http://www.flipkart.com/msi-nvidia-geforce-gt-720-2-gb-ddr3-graphics-card/p/itme3frcg78gnpkh?pid=GRCE3FRCRCDG8KGY&srno=b_40&ref=04dddca6-c87f-4ce7-ae2d-e90c083143bf

http://www.flipkart.com/forsa-nvidia-gt620-2-gb-ddr3-graphics-card/p/itmdb7pmrgchhfcz?pid=GRCDB7PMRGCHHFCZ&srno=b_36&ref=04dddca6-c87f-4ce7-ae2d-e90c083143bf

http://www.flipkart.com/zotac-nvidia-geforce-gt-610-synergy-2-gb-ddr3-graphics-card/p/itmdv9zb9gpqn2ja?pid=GRCDBM6PDGC9QJEZ&srno=b_30&ref=7fdb6f41-469a-41cd-bef8-f9fcd06cd19c

http://www.snapdeal.com/product/zotac-nvidia-geforce-gt-720/634994473831#bcrumbLabelId:305

now they are all different (the gt720 is also different) ,now if you pls can kindly see them and advice which one to get for the reason i specified and if they will be compatible with my computer specs mentioned above.
Or If you can advice something better but in the same price range as above that would also be great.

I really would appreciate any help you guys can offer me,i'd be really grateful and thanks in advance

Regards
P.s - Now I think this should be in the Systems section ,so i'll post one there ,sorry for the double post