Internet Explore 9 in Win7 doesn't save drop down parameter choices
In IE9 in Win7, if you change a component's parameter drop-down value, save your pipe, leave and come back to editing the pipe, you'll see the parameter value is now set to a newly inserted blank entry at the top of the drop-down list, instead of what you chose. This does affect (break) running the pipe too.
SP announced support for IE 7 and 8 in 2010. I don't have a box w/ IE7 or 8 to check on this atm.
I plan to update our help w/ info to not recommend IE9.