Windows wont eject USB device.

I have an XP laptop that has some funky USB driver action going on and refuses to let me "Safely Remove" some devices; also my Vista desktop has a powered USB hub that refuses to eject anything at all so I went looking for a USB manager and found USBDeview.

Its a portable (ie no install) application that will show you every USB device installed on your system and its current state.

This gives you full control of your USB functions, like allowing you to uninstall any USB device even if its not plugged in or won't register on insertion and to properly eject most devices cleanly.
Usbdeview also has the ability to autorun any file on device insertion (like Antivirus scan etc) and has command line switches available. Tested on XP 32 and Vista x64, worked perfectly and did I mention its free ?

If you are still having problems getting your OS to let go of a device you can use Process Explorer to find out what process has hold of it.

Process Explorer has a huge amount of information about your running system and makes an excellent task manager replacement on all Windows platforms.
To find that allusive process : Open Process Explorer and go to the Find menu. Type in the name of the device (which you can get from the USBDeview description) and it will show all the processes that have it open, I have used my Xbox 360 controller as an example in the picture below.

As you can see the application XboxStat.exe has the controller open, if I double click it it will take me to its place in the process tree were I can end task it if I want. Be careful what you close, if you have to close explorer you will lose your taskbar and any explorer windows that are open. If explorer doesn't start back up automatically go to Process Explorer / File / Run and type explorer
Hit enter and your shell should come back.