I recently watched an excerpt of Giselle featuring Lorena Feijoo in Giselle showing a solo variation in act one that I have not seen or heard before. The music is mainly played by a flute and the variation starts with entrechat quatre - balloté par- terre - jeté and ends with the typical manège of tours piqués... Is this on music by Adam? Who choreographed this variation? Is it included in the pas des paysans?

That sounds roughly like the variation from the 1884 pas de deux added by Petipa for Maria Gorshenkova. The music is by Minkus, possibly souped up a little by Drigo. Whose choreography it is is a debatable point. I don't think that it's part of the notated score.

Isn't that variation part of that added Minkus PDD that is in the Nureyev/Seymour production...? ( I think i started a thread on the subject a while ago)

I found the link of that older thread...Here it is:
http://ballettalk.invisionzone.com/index.p...aded&start=