Get-ADUser with the -LDAPfilter using a regex

I'm by no means a novice to PowerShell, but for my first year and 1/2 using it the organization I worked for only had 2003 AD functional level, so to do AD stuff I needed to use the Quest Active Directory tools (get-qaduser). Now that I'm working for a place that is a bit more modern on their infrastructure, I just can't seem to wrap my head around get-aduser stuff when dealing with filters and LDAPfilters - AKA, "I'm used to QAD being easy, please help!"

Could someone give me an overview with lots of examples?

Thank you.

zarberg@gmail.com