Hi Dave,
You don't mention what your set up is but I assume it is a 1394 Pyro card or similar (OHCI type )
Stick with the PC, there are many sucessful Video editors using such a set up.
I use the PYRO card with the bundled software ( media studio pro V 6.0 ) which is all an amateur will ever require as it is a very comprehensive software.
Have a look at these foruims and post your questions there. You will find them a helpful bunch ( like this one

)
http://pub9.ezboard.com/bpyro1394
http://www.creativecow.net/cgi-bin/select_forum.cgi?forum=ulead_mediastudio_pro
The first one has a lot of useful FAQ's
If you can get a Bundled PYRO card with software cheap ( I got mine for about 70 GBP in UK ) that might be your best bet, as you can always run firenet, a networking software and make use of your other card if you get a second PC.
As for XP, don't know current situation with drivers but forums will tell you.
Good luck
Al