DSDT Patching fixes a problem with the RTC (real time clock) in the 10.5.6 update which will affect all OSx86 users. Therefore, the DSDT must be patched for you to be able to run 10.5.6.
There are already powerful tools available to patch and apply a modified DSDT, but up till now people have feared doing this as it is a "complicated" procedure. Now with the GUI version of fassl's amazing DSDT Patcher anyone can do it. The DSDT patch will be generated, patched and installed just with one mouse click.