The best way to automate tasks on the server is whatever works the best for your situation. There is no one size fits all automation tool.

As for Powershell - if you are running SQL Server 2008 (you posted in the 2008 forum, so I am assuming that is what you are running), then Powershell is already installed. SQL Server 2008 comes with it's own version of Powershell that you can automate through SQL Server Agent - or Task scheduler.