I would say that a 'firewire card' is a type of 'capture card'
Capture cards can be Digital or Analogue. Your D8 camcorder will have a firewire output, so you should get a firewire card. These only cost £10-£20 from ebuyer etc. There really is no need to spend more money on a 'brand name' card as they are ALL good enough for video capture. All you will need then is software. If you have Windows XP then you already have Movie Maker. Upgrade to MM2 from the MS web site (free download

) and you have a full setup for the cost of the capture card.
If you do not have XP then you can buy a firewire card from around £20 up including software. All capture cards should include a cable to connect your camcorder to the card.
To edit on a PC you will need a minimum of:
Windows 98SE (first edition will NOT work)
1Gb of disk space for every 4 minutes of captured footage
Of course once you have started you can (and will

) spend more money upgrading the PC to make editing quicker and with better results

.
Good luck,
Mark.