Problem downloading video recorded on different camcorder

I used a Sony miniDV camcorder for several years and recorded a lot of video. I bought a Sony HDR-HC7 High Def camcorder and am now trying to download some of the video tapes I recorded on the old Sony camcorder. The video clips chop short and the I can't understand the audio. I'm using imovie 06 and a PowerPC G4 loaded. I think I may need to buy a camera like I had and play the tapes back on it. What do you think? I'm pretty sure I have the setting on the camera and computer set properly.