OP: Judging by your post, you are expecting an uber high end PC for your needs. Now, I assume that you know your hardware, its just that you are not in touch with the current scenario. If my assumption is right, then you must be knowing that there is no such thing as futureproof hardware. I dont know how people can claim that such hardware will last you for so much time or this wont. Actually nobody can tell what H/W will last how many years. The most sensible thing to do when you are building a PC is to decide a budget (that you did) and look for parts that give you the maximum performance TODAY and HOPE that it will last you the longest judging by the current scene.
ATI 58xx are the first generation DX11 cards. They give excellent DX 10 performance and good DX11 performance. Bear in mind there is exactly one DX 11 game right now. But we shd see DX 11 games coming in Q1 2010 and shd be flooded with em by Q3 2010.
When I look at the benchmarks:
Dirt 2 benchmarks - DX 9 vs. DX 11 - Update: Radeon HD 5970 results - Colin McRae Dirt 2, DirectX 9 vs. DirectX 11, Test, Benchmark - PC Games Hardware
I notice that the minimum card you want to go with is a 5970 if you want full eye candy at FUll HD resolution.
For the rest of the rig, follow what Anubis has suggested except for a few changes from my side:
Processor: Intel Core i7 920 - 14.5k
Gigabyte EX58-UD5 - 16.1k
GPU: ATI HD5970 2GB GDDR5 - 40k
HDD: WD 1TB SATAII BLACK - 5.5K (significant performance gains over the seagate mentioned by Anubis
Cabinet: Coolermaster HAF 922 - Rs. 7436.
http://www.techenclave.com/dealers-paradise/coolermaster-cabinets-shipped-prices-152832.html
SMPS: Corsair TX 750 - 7.8k
Keyboard: Logitech G15 -4K
Mouse: Logitech G5 - 3.2K ( I would much rather go for Logitech G500 if you could get it from US. Its about 55 USD on Newegg)
RAM: if its for gaming and you feel you are on a tight budget go for 3 GB for now and upgrade to 6GB later. You wont see a difference. Most of the games that I play dont go over 2.5 GB (this includes the total memory consumption by the system)Add a CPU cooler to your config (SCCF - 2.5K) and overclock your processor.
Total - Rs. 105336
If you go with 5870 with all the other components same as I suggested
Total - 89K
For a monitor, you tell me what size you want? I will tell you the best monitor for the size and/or price
I have two other builds to suggest, if you find this overpriced.