I forgot to mention that the most convenient place to put this function is in your profile. What's that? You don't have a profile? Well What are you watiing for?
Make a folder inside your Documents folder called WindowsPowerShell. Inside that folder create a script called Microsoft.PowerShell_profile.ps1. Think of it as .bashrc for PowerShell.
I've uploaded my profile as an example here.
Also, note that I'm searching under the path pointed to by the PSPATH environment variable. I have it set to C:\PSLibs in my profile.