Ok lets go through a basic check list of things to do and see if we can start to fill your HDD with video
connect cam to PC with firewire
put cam into replay mode (VCR type controls on cam should now be available)
start Adobe (I assume this is Premiere) software
click on 'file' then 'capture' (and then any other required options - don't know Prem 4)
From the capture window you should now have a set of VCR buttons that should be able to control the cam
If you have any problems with the above then let us know if any error messages are displayed.
To check if the firewire card is installed correctly you can go into 'Control Panel' 'System' 'Device Manager' and look for the firewire card (may be listed as ieee1394). Does it show in here? Does it have a yellow circle with an '!' in it beside the card? If you do have the '!' displayed then the card has not been fully installed. If you are running Windows 98 (and not 98SE) then I would really suggest you upgrade to at least 98SE as the origional 98 did not support OHCI cards (USB & Firewire) and even with driver patches is unlikely to work smoothly.
HTH,
Mark.