Mixing 10/1000 Device w/ other Gigabit Devices to Apple Airport Extreme My Mac Minis (which support Gigabit Ethernet) are physically connected through Gigabit Ethernet to my current generation Apple Airport Extreme (which has Gigabit Ethernet switch ports).  

If I add a Apple Airport Express (which is a 10/100 Mbps device does not support Gigabit) will it negatively affect network transfer speeds between the Mac Minis?  Because it's on a switched network it shouldn't right?  Will I experience flow control issues?
No - switches isolate things so you don't need to worry about hub-like limitations.