Converting from 8mm Video Tapes to Digital (PC)
Three years ago I purchased the DIAMOND One Touch Video Capture similar to the 2nd link you provided.:

http://www.newegg.com/Product/Product.aspx?Item=N82E16815306013

This device worked perfectly for converting tons of old VHS tapes to a format suitable for DVDs, I must have converted over 50 tapes this way. I also discovered that I could use this device to capture live broadcasts using the following chain: Antenna --> Video Converter box --> Diamond...Capture --> USB Computer input --> capture software.

The main thing you have to remember is that the conversion is in real time and linear. I had to allow for the tape to play through the parts I wanted to capture at the normal playback speed. On the plus side, the USB interface allows quick and easy set up, no need to open up your computer and install another PCI card.