Now i know that except my Harddisk and possibly my processor and monitor [i cant afford to buy those if i need a gpu+ram+psu] , i need to change everything. So this is my idea , please let me know if you think its fine or otherwise.
I go for a ,
1. 650w PSU worth 2.5k INR.
2. Radeon HD 6870 worth 12k INR. and
3. 1x 2gb DDR2 Ram worth 1.5k INR.
Which is 16k INR in total , just above my budget but that's fine. [My budget is 15k]
Based on my web research and all , i think ill be able to play games like Crysis 2 and all in moderate settings with those upgrades because untill now i was able to play all games like crysis 1 and warhead , Assassins creed revelations at low settings with 30-35 FPS.
I am not looking for a mega GFX card cause i seriously doubt that i will be changing my 15 inch monitor.
The REAL reason i am asking you this is that my friends told me that 6870 would be like a whale in a pond with that small monitor of mine so , IF i can substitute my GFX i.e the 6870 TO ANYTHING similar with regards to my 15 inch which can fulfill my end goal which is to play all the upcoming games till 2015 atleast at either moderate , or just in the middle of low and moderate , then it would be a great help.
^DDR2 is his only choice without changing the mainboard. And yes for better performance 4GB is a must.
I think, that in your case, you should be looking for used parts rather than new.
New DDR2 Ram is very expensive. Also what is your display resolution? For 15" I guess it is about 1366 x 768. HD6870 for that resolution is an overkill, so is the 650W PSU for this card. Also, the e7400 will bottleneck 6870.
My advice is:
1. Buy used Q6600 or other quad core for socket 775, if your mainboard supports it.
2. Add RAM to have 4GB
3. Look for best possible used radeon from 5xxx series within your budget. 5850 will be all right, but still an overkill.
4. Buy a new, quality 500-600W PSU.
They still make DDR-2 modules but they are way over priced now. Also ilovedevilmaycry a 6870 is indeed over kill for a 15 inch monitor. Get a 6770, 7770 if you plan on keeping the 15 inch monitor and you will be fine.