Oh, they've got some amazing music. Please add more of their work (and not just holiday stuff) to the playlist. I highly recommend the CDs "The Rose" and "Undrentide" (look for the track "Aria" with Delerium on the latter). When you happen to be in place that sells used CDs, keep an eye out for CDs by Miranda Sex Garden, too. Some of the founding members of Mediaeval Baebes were formerly in Miranda Sex Garden, so the sound is very similar.
I had gotten some Medieval Babes music as part of a sampler on a Pizza Hut promo, and I really liked it. I will have to look for this recording to add to my collection.