Im sorry if this is repeating whats already been mentioned, but I couldnt make myself read all the messages in this thread.
Well, i have been a fan of scandinavian folkmusic for some time now and I also play some odd intruments meself.
There is a lot of different characteristics amongst the scandinavian folklore scene, and I would divide the scene into two major groups. First the one that play old songs as they probably where intended to be played and of course creating new material wich could just as well have been created long ago.
On the other scene theres the bands that take old songs and rearrange them with a modern touch and also often with some help of modern instruments.
Now I would think that someone that likes the Vintersorg type of music would like music with some tempo in, and therefor I would recommend these bands:
Hoven Droven pretty famous band that plays folkmusic with a lot of tempo and also guitars and saxophone. Very good!
Find them at:
http://hovendroven.op.se/
Hedningarna Sometimes a bit hardlistened, but very very good. Find them at:
http://www.cabal.se/silence/nyhedning/
Urga now this is odd, they invented a language of their own and all songs are made in "Urgian" as they call it, but if this doesnt make you dance, nothing will. Try the song "Allo manne".
Find them at:
http://www.silence.se/urga/
Garmarna The all famous band from Sundsvall Sweden took on the world and conquered it ;-) Well, this is probably folkmusic as good as it gets.
Find them at:
http://www.cabal.se/massproduktion/garmarna/
Now some bands that play a more "hardcore" folkmusic as it probably was intended to be, and what I recommend is:
Sorkar & Strängar These guys make their own music, no modern instruments at all, theyre the band that will be playing in the inner most corner of the dark tavern in the medeival town you visit, and the songs are mostly about alcohol and lost love
Find them at:
http://sorkar.com
Wolgemut These guys play music mostly based on rythm and bagpipes. Not the general scottish warpipe, but the medeival renessance pipe, but its impressive nonetheless.
Find them at:
http://home.t-online.de/home/320041873729/index.html
Corvus corax the name means raven in lathin and these guys plays also medeival bagpipemusic, but perhaps with a little bit more bagpipes ;-)
Find them at:
http://www.corvuscorax.de/
Visby vaganter Plays medeival folkmusic mostly for the event caleld "wisby medeival week"
Find them at:
http://gotland.net/wisbyvaganter/
Gravrost Folkmusic best heard live.
No site availiable...
Well thats what I can come up with right now, I might be able to get some more with some time on me hands.