The iRiver PMC 100 series consists of the PMC 120 which is the 20GB model and the PMC 140 which is the larger 40GB model. The iRiver PMC runs Microsoft portable media center so you will need a Windows XP pc to connect it to.
The iRiver PMP-120 portable media player has the ability to play audio and view images and video on it's 3.5 inch 320 x 240 pixels TFT screen. It also boasts the ability to record audio and has a built in FM tuner. The PMP 120 lack a video recording capability but can output to a video device such as a television.