The P5Q would work as well, for that matter you could go for a p43 chipset if you wanted and save even more, but you are decreasing your ability for stability when overclocking. The P5Q isn't as good as the UD3R. Apparently India gets better deals on asus than gigabyte boards though...
Yeah I guess so. Besides, I won't be overclocking that much. Meaning, I would just play around a bit and go back to default settings. So P5Q should pretty much suffice.
And about the Vista Home Premium.. I haven't actually used it till now. Would the media center and aero interface make it worth getting over the home basic version? I'm guessing, since I'm getting 4 gigs of memory, i could go for it anyway?
Arctic Sliver Ceramique is good - but Arctic Cooling MX-2 or OCZ Freeze might be a bit better. Thermal Compound Review
Edit; I saw the Arctic Silver Ceramique CMQ-22G 22 Gram Syringe for Rs :313.00. 22grams is a LOT! of thermal compound. Most of the others have 3.5 or 4grams. And Rs313 is too low a price for that much. Arctic Silver Ceramique also comes in a 2.5gram package and I think that price could be Rs313.
Arctic Silver Ceramique 2.5gram USD $4.99
Arctic Silver Ceramique 22gram USD $9.99