If this is the first time you have heard of PRAM or you aren't in the habit of zapping it, there isn't a good reason to start. In a study one company did on which trouble shooting techniques worked more of the time, zapping the PRAM was of assistance only a small fraction of the time. In normal use of your Mac files are segmented into multiple physical pieces on your hard drive. Although this is normal, and the way your Mac was designed to function, fragmentation can lead to problems over time if it isn't kept at bay. If everything is functioning properly the most serious problem caused by fragmentation will be poor performance.
Fragmentation taken to extremes can lead to corruption of files and lost data.
A drive with little fragmentation is also much easier to repair or recover if problems do occur than one with more severe fragmentation. Once you've backed up, cleaned up, checked out, rebuilt, and optimized your Mac you can rest in the fact that you've done just about everything possible to protect the investment you've made in setting up your Mac and the time and energy contained within each one of your files. Following the guidelines above will allow your Mac to perform years of service with those nagging crashes farther apart and more time with your Mac smiling at you and you smiling at your Mac. Really Mac maintenance is a matter of choices. Pay now, or pay later.