Yes, you can. Just check the size of the steerer tube, as you may have to cut it to size to fit your frame.
Make sure you buy a fork with the right amount of travel for wht you use the bike for. A lighter, shorter travel (75-100mm) one such as the Dart or SID for XC use, and a heavier, longer travel fork such as the Pike or Boxxer for Freeride/DH use. Remember, the longer the travel, the hevier the fork wil be.
If you run V-Brakes, make sure it has the mounts for them, and look out for disc mounts if you ever feel like upgrading.
I've found Rock Shox to be the best forks.
