Hello,
where can i buy windows 7 professional multiple license for my office workstations.it's a branded system with windows xp professional now want to upgrade to windows 7 professional.please help me out
Depends on how many licenses you need. If it's just a few, then you probably won't qualify for a volume discount. If it's dozens, you probably want to look into MSDN.
If you require 5 or more then you'll probably be better of getting them on a MOLP/MOV (Microsoft Open License Plan/Microsoft Open Value) these need to be bought through an authorised Dealer/Partner.
More info on volume licensing here --> http://www.microsoft.com/licensing/