Ps3 vs ps vita? Plus bonus question!?

I wanted a ps vita but I'm not sure if I should wait for the ps vita or just buy a ps3. Is the ps3 still more powerful then the ps vita? The bonus question is those little NVG cards that the ps vita will use instead of umds will they be noisy like umds? Sometimes it is annoying hearing the umd rattle whenever you play a game on psp.