To mount the partitions of a vmdk file (read and writeable) under windows you can use the tool vmware-mount (part of the vSphere 5 Disk Development Kit).
You can download it here: vSphere Disk Development Kit
After installation you need a commandline. With the parameter -h you will get a quick overview about the syntax and the possible parameters:
To mount a vmdk file (saved at C:\temp) in read-only mode use the following command:
vmware-mount.exe X: “C:\Temp\TestVM.vmdk”
Now you have a read-only access to the vmdk file using your windows explorer (navigate to driveletter X:).
If the vmdk file contains more than one partition you can use the parameter /v:x to mount the other volumes:
vmware-mount.exe /v:2 X: “C:\Temp\TestVM.vmdk”
If you need a writeable access just use the parameter “/m:w“.
This is extremly helpful if you need to replace a broken systemfile for example:
vmware-mount.exe /m:w X: “C:\Temp\TestVM.vmdk”
To delete the mapping to driveletter X: use the parameter /d:
vmware-mount.exe /d X:
And last but not least – if you want to list all the mounted virtual drives use /L: