you just need a regular TV tuner with Analog video inputs to capture from your Bell satellite receiver but I would suggest getting one like the ATI Theater 550 which has a breakout box for the inputs. Also this tuner has a chip for hardware video encoding for MPEG2. Hauppage cards are also good, they are used massively on commercial HP systems. You have a tv tuner review here
http://www.anandtech.com/show/1661/9 .
Consider getting a SSD as boot drive, I have Win7 Ultimate x64 on a 30GB and there is space left after installing a few programs. The Seagate you have is good for storage but don't make it a boot drive.