Fast internet connectivity and download speed does not depend on your PC configuration. They depend on your broadband speed (2Mbps or so) and your service provider.
This is a good and affordable configuration for a mid-range PC
Tech2.com India > A Multimedia PC Under Rs 35,000 > Features > PCs & Laptops > Desktop PCs . Check this out.
Get a Pixelview Play TV 415 USB TV tuner (about Rs.2200) if you have multiple PCs (PC and laptop etc) as this is a plug and play device and can be carried around. Otherwise buy an internal TV tuner card from Pixelview/Pinnacle/Compro (about Rs.1700).