Windows 7 deployment

I have 300 pc(think center/lenovo) using windows xp on all.I want to deploy windows 7 and install it on all the pc but once a time to consume time.I don’t want to upgrade each pc alone and from cd.is there way to upgrade windows xp to windows 7 for all the pcs at the same time or for group of pcs.
note that I am using Altiris deployment software.