Grabek, I have a Sony DCR-TRV50 that I bought 4-5 years ago, looking at the specs your DCR-TRV70 is almost the same.
To make a home movies in DVD quality, you need the following:
1. MiniDV tapes
2. A Firewire 1394 card for your PC or laptop
3. A Firewire cable 4pin to 6 pin to connect your camcorder (with the 4pin) to your PC (6pin). You can search for a cheaper brand if you don't want the expensive Monster Cable.
4. A DVD Authoring software such as Pinnacle Studio 9 or Ulead DVDMovie Factory 4.
How to make a dvd movie:
1. Buy MiniDV tapes and record in camera mode. The camcorder will record Video/Audio into the tape. Do not record in Memory/Network mode as this one will create a low quality video in your memory stick card.
2. Connect your camcorder to the PC using firewire cable.
3. Capture the video from your camcorder with Pinnacle/Ulead. You need at least 12GB harddrive space for an hour of movie.
4. Author the movie, add menu, text, transition effects, special effects etc.
5. Burn to DVD
Another way is to capture the movie from your MiniDV tapes in analog format (not digital) to an analog capture card (more expensive than firewire card) or directly to VHS. You can buy a Mini AV to Composite Video and Audio or if your VHS/analog capture card have an S-Video input you can use a S-Video cable in exchange to the analog Video cable above.
The USB cable is good only to capture digital still images or low quality video (when you use the Memory mode) from your memory stick card.