What he said^^^ and every plugin you have from 3rd parties will need to be updated(everything you have now is either RTAS or AAX32 and PT11 on up only runs AAX64. The good news is; everything has been updated in one form or another(TDM plugins are another discussion). The "bad" news is that a handful of stock plugins have been updated in a way that means the old versions(from your old sessions) will need some fussing to get things sounding the same(example; the digirack delays of SHORT, MEDIUM, etc have all been replaced by a single delay plugin that covers all). On the good side, full 64 bit support is well worth the effort
