castrox (630511) writes "It seems Microsoft have taken a notice that users may want to run XP instead of Vista. The new deal is to simplify downgrading for the OEMs. Currently, all OEMs must call Microsoft whenever a downgrade is done. After this "simplification" OEMs may submit batches of keys to Microsoft which will save time.
According to the Microsoft blog on ZDNet, the "downgrade software" will still need to be supplied by the end user. The deal is rather perplexing — it does not seem like you can convert the license since the only eligible versions for downgrading is Ultimate and Business.
Effectively, it seems nothing has changed. More on the downgrade "rights" (warning: PDF) here."