This is an interesting issue: Some of our users couldn't bring up lists in SharePoint's Datasheet view, which makes the list appear almost like an Excel spreadsheet. The item was grayed out on the Internet Explorer 64-bit on Windows 7 64-bit. Solution? Use IE 32-bit. More on the issue here. It has to do with a 32-bit ActiveX control used to render the Datasheet View.
One other interesting item: Both of the IE shortcuts on the Programs menu of Windows 7 x64 are to the 64-bit version; it's somewhat misleading, because one has "(64-bit)" in parenthesis and the other doesn't, so one assumes the one without that is 32-bit. That's not the case. To run 32-bit IE, go to "C:\Program Files (x86)\Internet Explorer\iexplore.exe" and create a shortcut to it on your desktop.