yes, new soundcards typically only supply line-out signal levels which are not enough to run unpowered speakers. You need new powered speakers or run the output to your stereo (using the appropriate adapter)
As for what kind, that all depends on what you want. The minimum I would recommend is a 2.1 setup. This is 2 stereo desktop speakers and a sub and can be found for as little as about $25 (logitech s220 or Ls21)
simple stereo speakers can commonly be found for under $10 (logitech s120)
and full blown 7.1 setups can get very expensive.