Battery or Alternator issue? (1996 Passat GLX)

For a while now, the digital clock and trip odometer reset upon starting the car. There's a bit of a lull of energy as i turn the ignition, but then it turns over.
Its increasing in frequency, about 4 out of every 5 times i start the car or so.
It used to do this only about once or twice a month.
I've charged the battery, i've cleaned off the terminals and tightened the cables.
The other day it didnt start at all and i had to jump it.
(Incidentally, the radio stations do not reset: they usually reset when i unhook the battery completely...)

Could i need a new battery or alternator?

You might alos want to have the starter checked for drawing too many Amps. It could be pulling down the electrical system to too low a voltage.

This happened to my passat when I first got it. Almost everytime that I started my car the odometer and clock would reset. The problem went away once I replaced the battery. Hope this helps.