Medieval-style music

Some good recommendations have already been posted. In addition to the Hildegard von Bingen recording on Hyperion (a must have) and the general recommendation to consider anything on the Harmonia Mundi label that strikes your interest, I'll offer the following specific recommendations from my LP collection that are superb both musically and sonically (you'll have to see if they are available on CD if that is your preference):

If you like music of medieval Spain, try anything by Gregorio Paniagua (dir.) and the Atrium Musicae de Madrid. For me, all of the following are "must have":

* La Spagna (Bis)
* Musique Arabo-Andalouse (Harmonia Mundi)
* Tarantelle (Harmonia Mundi)
* Villancisos (Harmonia Mundi)
* La Folia (longterm audiophile favorite; rollicking good fun and a bit bizarre) (Harmonia Mundi)

Performances by the Clemencic Consort on Harmonia Mundi are wonderful. I particularly value:

* Camina Burana (from the original manuscript, in 5 volumes on LP. Vol. 5 is my favorite, or choose the highlights disc)
* Dances Anciennes de Hongrie
* Dances Du Moyen-Age
* La fete de l'ane (Feast of the Ass)

Other miscellaneous recordings that are excellent and well worth seeking out include:

* The Dante Troubadours, Martin Best (Nimbus)
* Troubadour Songs and medieval Lyrics, Hillier (Hyperion)
* Songs & Dances 1200 to 1550, Kalenda Maya (Simax)
* Music of the Four Seasons, Joculatores Upsalienses (Bis)
* Early Music at Wik, Joculatores Upsalienses (Bis)
* Skogen, Flickan och Flaskan (Woods Women and Wine), Joculatores Upsalienses (Bis)
* Worcester Fragments,Stevens/AccademiaMoteverdiana (Turnabout)
* Sumer is icumen in - chants medievaux anglais, Hilliard Ensemble (Harmonia Mundi)

Good luck in your continuing exploration of ancient music!

Between Flex's and Rushton's recommendations, you got yourself a very comprehensive list. They nailed it!. La Spagna is a bit hard to find since it's out-of-print.

If you're interested in 12th century French polyphony in addition to secular music, another well-known cd from Harmonia Mundi is "The Age of Cathedrals", with Paul Hillier and the Theatre of voices.

Another to consider, also on Dorian, is "Echoes of Spain" a disc of medieval Spanish and Portuguese by Sonus

There is always Steeleye Span who did English medieval sounding (maybe authentic) stuff back in the 1970's. "Parcel of Rogues" and "Storm Force Ten" are two that I have but haven't listened to in 20 years. I recall enjoying the former.