Hi!
Well, I read the whole thread and it appears to me that the thread starter is just looking for a good pc which is future proof(in layman's terms) and could play everything that he throws at it.
So, Nihu, let me suggest you something good for you. I understand that you want the latest stuff like ddr3 ram, 4 core processor and graphics card and all. But let me tell you buddy, these all things are overkill for your purpose of watching multimedia content on your HDTV(assuming that you're gonna use the htpc on a HDTV).
Get an AMD 7750 processor for rs 3100, an Asus or gigabyte motherboard(with HDMI, DVI, VGA, optical audio out, 7.1 analog audio out, embedded ati 3200 graphics) for around rs.4000.
2 sticks of 1gb ddr2 ram at 800fsb of any good brand like kingston, corsair or transcend...whichever is available to you easily in your locality.
get 1 TB hard disk because HTPCs are supposed to be stuffed with media. You can store all your songs, images, high def movies, DVD movies, etc etc etc.
A branded cabinet(with smps) like iball, zebronics, cooler master, etc etc...
a dvd writer or a blueray reader cum dvd writer(if you wish to play blu ray discs on hard copies instead of the downloaded ones)
a wireless multimedia keyboard and mouse of a good company(be sure that the mouse you're getting has good battery backup else you'll be bugged up by having to change batteries in every few days)
Now, this dual core processor is enough for playing and occasionally encoding all the movies/video/files you throw at it. The graphics chipsets have advanced to a very modern stage and ATi 3200 is a real champ for HTPC's and light gaming like counter strike, NFS, etc, etc on mid settings. Ram 2gb in enough, and btw if you buy 4gb then you wont be able to use more than 3.37gb because the 32bit operating systems can only address this much. Rest will go waste unless you choose to install a 64bit OS which is highly unlikely because the compatibility issues are deal breaker. And be sure that you buy 2 sticks of 1 gb ram coz it will give you DUAL CHANNEL performance, if you just get a single stick of 2gb then it wont do the same.
here you have a good config for an HTPC, light gaming and a general purpose pc.
Item Cost Warranty
Processor rs 3100 3 yrs
mobo rs 4000 3 yrs
Ram(2*1gb) rs 1400 3 yrs
HDD 1TB rs 4500 5 yrs
Cab+smps rs 1500 1 yr
DVD writer rs 1100 3 yrs
keyb+mse rs 1200 3 yrs
card reader rs 200 0 yrs
HDMI Cable rs 500 0 yrs
===================
rs 17,500
Approx Rs 18000 and you have yourself a very nice HTPC(excluding a bluray drive) with all the modern emenities and huge storage capacity.
You can deduct the price of the components which you already have, but in my opinion it's always good to have new stuff which compliments your new setup.
And let me be clear, if you get that Lenovo desktop, or another branded desktop then you will be paying anywhere from 30-50% extra for the same stuff which you can assemble. And not to mention the warranty, which is only 1 year standard. You can extend it, but it will again cost you a bomb. It's always better to build your own thing.
I didn't suggest an intel config because intel boards dont have decent graphics chipset for a reasonable price. AMD is a good choice, don't be bothered by foolish people who say that AMD is not good, AMD is slow or AMD heats up too much...all's crap, I am using AMD in my main desktop, HTPC and my laptop. It rocks!
Hope it helps.
Deepak