I'd advise getting a hardware encoder, which means the card does all the hard work and your PC if free for you to use.Leadtek
I've got this.Hauppauge
From what I've read the Hauppauge cards have a macrovision decoder inbuilt, which means you shouldn't need a seperate box to remove macrovision. Just search for Provision Macrovision on google.co.uk
Personally I'd stay away from the cheap software encoders at about £25-£40 and get a slightly more expensive hardware encoder.