yes it is possible if you create a site for that project then upload to it the documents you want office document pdf or jpeg or any other docs you want.
to creat a site just log in to your PWA press the admin tap then select form the side pane:
Manage Windows SharePoint Services sites
then under options select :Manage SharePoint sites
you'll see a list of your enterprise projects select the one you want to add document to it and then press on create a site follow the link to find that a site is been created with documents risks and issues.
upload the documents you want.
then to attach these documents to tasks, in the task view click on the task and then on link documents on the top bar
and here you are attaching a document to your task
you are most wellcome
EggHeadCafe.com - .NET Developer Portal of Choice
http://www.eggheadcafe.com