What kind of PC is it? What kind of FireWire port? 6-pin or 4-pin? If you go into Device Manager, can you see your FireWire (IEEE 1394) port device? If this is a desktop PC, is it an OEM (Dell, HP) or a home-built? Is this a front-panel FireWire, or it is on the back of the PC? If it's a front-port, but motherboard does not have a header for it, it could simply be not connected. If it's a laptop and only has a 4-pin port, I found that those 4-pin ports on PCs never worked right. You generally want a 6-pin.
What USB-FireWire adapter did you get? Just a pin-adapter you can get for about $5 or an actual conversion box? Proper FireWire operates at a much higher voltage, and those pin-adapters are strictly special-application stuff.
In any case, if this is a desktop PC, and the port is on its back, you need to make sure in the device manager that the port is active. Ditto if this is a front port and actually connected to a proper i1394 header. Otherwise, you will need a FireWire add-on PCI Express card.
Panasonic may not have released camcorder drivers for Win 7, but you should not need them. There are generic DV device controller drivers that come with Win 7. If anything, download Live Essentials, including Movie Maker - it should have the driver. I have a Sony camcorder that is over 10 years old, and Win 7 recognizes it. Btw, you DO turn on your camcorder into 'VCR' mode when you connect it, right? Windows will not recognize a turned-off camera.
I recently went through my miniDV archive, and captured all my taped to hard drive. I used Scenalyzer
to capture. It is a very handy and easy to use bit of software. Breaks up your video into individual scenes, and includes the date/time of the recording in the file names. Adobe Premiere also can capture and break up, but it does not save the date/time of the recording.