Right, the simplest way to delete a locked file is to boot in using another OS when Windows is not accessing it. This can be done fairly simply, either using a Linux LiveCD or a preinstalled environment such as WinPE, or a create yourself clone like BartPE. This will allow you to boot up into an environment where you can mount the drive and navigate to the directory where the locked file is an delete it. I've done this myself using BartPE and it's worked me wonders. As for the partition problem you have a few options. You can try and use a Linux installation CD and use that to repartition the drive, but I'm unsure as to whether this is non-destructive or not (if the data gets wiped and then repartitioned or if your data will still remain there). There are also partition managers that can be installed on a LiveCD such a Gparted, etc.
Or you could also use a partitioning program like PartitionMagic. I think this was purchased by Symantec, however once installed (on another machine that's accessible) you can burn a boot CD that you can use to repartition the drive on the other machine. I've used PartitionMagic lots of times, and it's a pretty solid program. However this isn't free.
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