If you are doing basic FEA from time to time, the Pro/Mechanica module (also from PTC) may be an appropriate solution for you. You may want to call PTC and talk to somebody about whether it will fit the bill for you.
There are plenty of good FEA codes out there (and I'm somebody else will give a recommendation), but if you are only occassionally doing FEA work (and the mechanics complexity is fairly limited), your most important detail to buy a FE package will be the ease of going from your CAD to a mechanics model.
Either look at Mechanica, or else another FEA code which can integrate well with Pro/E.
Brad