When you play games in VMware it's quite useful to be able to lock the mouse inside the vm. Normally when VMware tools are installed, it automatically ungrabs the mouse when you leave the window. To change this, edit ~/.vmware/preferences and add:
pref.motionGrab = "FALSE" pref.motionUngrab = "FALSE"
Edit the vmx-file for your virtual machine and add:
vmmouse.present = FALSE
And that's it. You can switch the grab-state with the keyboard, by default it's bound to CTRL+ALT.