Serlet spoke at WWDC 2006 on the perceived similarities between Mac OS X Tiger and Windows Vista, including comparing Apple's Aqua interface and Microsoft's Aero interface. He poked fun at the apparent visual similarities and referenced a 2004 WWDC banner that read, "Redmond, start your photocopiers" — a reference to Microsoft headquarters, which is located in Redmond, Washington.[6] He also spoke at WWDC 2009 and gave an in-depth demonstration of Snow Leopard, which included further references to Microsoft's Windows operating system — claiming that Windows 7 is just another version of their widely criticized Vista release, citing the ongoing use of the Windows Registry, DLLs, the User Account Control (UAC) subsystem and existence of an interactive disk defragmenter.