lsof for windows

I was on my sister's computer (Windows XP) today because she wanted me to format her new external hard drive for her. Unfortunately, some program prevented me from doing so (it was accessing the device). I disabled the usual suspects (anti-virus, Google Desktop, etc.) but to no avail.

Unfortunately, Windows doesn't have anything like lsof which lets you see which processes are accessing which files. After a little bit of googling, though, I found the excellent Process Explorer. This program was written by Sysinternals (which has since been bought my Microsoft) and gives access to all sorts of useful information. In particular, you can search for a handle (for example, "F:\") and see what process is using what resource (in my sister's case, it was apparently mim.exe, which probably has something to do with MusicMatch or something...)

I wonder why Microsoft doesn't include something like this by default though... (the task manager is woefully inadequate...)