from the MSDN doco:
“The Execute Process task runs an application or batch file as part of a SQL Server 2005 Integration Services (SSIS) package workflow. Although you can use the Execute Process task to open any standard application, such as Microsoft Excel or Microsoft Word, you typically use it to run business applications or batch files that work against a data source. For example, you can use the Execute Process task to expand a compressed text file. Then the package can use the text file as a data source for the data flow in the package. As another example, you can use the Execute Process task to run a custom Visual Basic application that generates a daily sales report. Then you can attach the report to a Send Mail task and forward the report to a distribution list.
When the Execute Process task runs a command-line application, it provides input to the application through a variable that you specify in a property setting. The Execute Process task also includes properties for specifying the variables that consume the standard output and error output of the application. For more information about variables, see Integration Services Variables and Using Variables in Packages.
The Execute Process task can specify the command prompt arguments that the executable file or batch file requires. For example, if the task opens a document in Word, the command prompt argument can name the .doc file. You can use multiple command arguments in one task by using spaces to delimit arguments.
Additionally, you can configure the Execute Process task to specify a working directory, a time-out period, or a value to indicate that the executable ran successfully. The task can also be configured to fail if the return code of the executable does not match the value that indicates success, or if the executable is not found at the specified location.”