Other reputable brands such as Fox and Suntour make forks that may very well provide a good service life, but are not as well known for mountain bike forks. Rock Shox and Manitou make lower-end (but reasonably good) forks. Marzocchi has been making forks longer than anyone and has probably the best reputation, but they tend to be expensive so you won't find them on anything but expensive bikes. Most decent bikes are sold with Rock Shox, Manitou, or Marzocchi. The price will give you an indication of the fork quality. Find out the make and model of the fork, and search around on the web for it.
The cheapest forks also tend to be sold only on new bikes, and not separately.
