Don't Diss Macs Kamui.... They are more than suitable to perform the AMV task.
My advice to her is get Adobe Premiere 6 and get the Visual Quick start guide to Adobe Premiere (book) and allocate alot of free time to learn the software and just the same amount of free time to make a GOOD video...anybody could slap a video together in a day, but the good ones take a few weeks to do(not guaranteed though, good is a very subjective term).
I believe the ATI Raedon video cards and the new Gforce4 cards are Mac compatible, so get one of them that has video inpus as well as outputs so you can get cool clips from the original dvd and vhs source and use the software that comes with the hardware to get you clips. Bring your clips and music to Premiere and have fun!! This is your art, so there is no right or wrong, just public opinion, which sometimes is very insensitive and completely wrong and off-base.
Do your AMV for yourself first THEN after that you can deal with the sedated marketing research to appeal with the "masses". (Remember when you try to appeal to everybody, you appeal to nobody)
good video card
learn your software
place to host your finished product