By default, there are two virtual machines installed to "C:\Users\Username\Documents\Leapdroid\VMs". You may delete one of them to save about 500-800 MB space. The install file, LeapdroidVMInstaller.exe, is copied to "C:\Users\Username\AppData\Roaming\Leapdroid"; you may delete this file to save another 200MB.
[update] By default it uses too much RAM, so I modified the following line in \Documents\LeapDroid\VMs\vm1.vbox
Memory RAMSize="512" PageFusion="false"