Hi jobarde and welcome

Do you have a CCD-TRV300E or a DCR-TRV30E?

The DCR-TRV30E is a digital camcorder but the USB connection is not supported in Vista or Windows 7.  You will need an iLink/Firewire cable to transfer Video to your Windows 7 computer.  No drivers are required and you can import into something like Windows Movie Maker.

The CCD-TRV300E is fairly old now and records onto Standard 8mm or Hi8 tape.  The recording is Analogue (Composite Video or S-Video) and is older than more recent digital models.  You cannot transfer the video using a modern USB or Firewire digital connection.

How are you trying to connect to your Windows 7 computer?

http://www.sony.co.uk/support/en/topics/videotransfer#btn_HI8

You need an Audio/Video Cable and a computer with Analogue Inputs.  Most Windows 7 computers do not have analogue connections, so you may need to buy a digital video capture box to convert the signal to digital USB like this: -

http://www.amazon.co.uk/ClimaxDigital-Camcorders-Satellite-playstation3-software/dp/B002Y4GTVO/ref=sr_1_5?ie=UTF8&qid=1343065258&sr=8-5

These are available from £10 to £150 depending on the features you need.  Google locally for "Video Capture Device"

As long as you have a connection converter I guess this is possible, but I am not sure where can you buy one.