okey - so you got multiple problems ;)
1) is the error in the tooling - do you have both the Seam and the javax api on the classpath ? does this change wether you are targeting AS4 or AS7 from within the IDE ?
2) runtime issues concerning use of seam/granitds on AS7 - this is a questio for the AS7/Seam forums - afaik Seam 2.x won't run out of the box on as7 before Seam 2.3 - but better to ask that runtime issue on jboss or seam forum.