i'd wait for 7 just because it's due in ~6 months at most.
If you don't have DVDA then 6 with DVD is amazing. 6 has all the features of 5 plus a couple new, but not necessary, enhancements. If you have duel core/CPU's 6 is a big boost, or if you want DVDA.
Eigther way, if it were me (and it was last year!) wait until the next version comes out. You get a $50 discount anyway. :)