Bill, you can download video from your cam to PC via USB 2.0 but it is slower and not as reliable as firewire. Your GS19 has a 4 pin firewire port and if your PC is also equiped with it (probably 6 pin) this is the way to go. You will need to purchase a 4 pin to 6 pin firewire cable. If you do use a USB port you will probably have to install the software that came with the cam, firewire requires no additional software.
If you are running Windows XP you should have Windows Movie Maker bundled in the operating system. If you are running a Mac you should have iMovie bundled in the system. After connecting your cam to PC or Mac open WMM (iMovie) and follow instructions on transferring video to your computer. Be sure WMM (iMovie) has recognized your cam before preceding. WMM is very limited on what you can with the video but it is a very easy program to use and does make good video clips formatted for internet use.
If you are wanting to edit the video/audio and make DVD's, VHS tapes, or transfer back to miniDV then you would be better served by getting video editing and DVD burning software.