I've just done a quick Google search and found a review by PCPlus mag which says that DV-in is enabled out of the box on the PC100E
Firewire cards are all the same unless they have hardware codecs. Therefore as long as it is a firewire PCI card (aka ieee1394 or DV) then it will capture full quality video from your camcorder. These cost from around £15 from the likes of Dabs etc.
You say that you are running Win XP, therefore you have editing software already installed. Movie Maker is part of the XP install, but is very poor. I would suggest you get on the MS web site and get the free download for MM2 which is far better.
Mark.