humm... doesn't seem quite ethical, to try "cheating" the system?

The first roadblock I can think of is: Is it even possible to obtain the VMware-Tools installer (legally) without buying Workstation (or GSX/ESX)? I think those drivers are needed to get decent performance from the VM.

Cheers to VMware for releasing the Player! (It's definitely helping me to convince management of the usefulness of VM's )

VMware does not place any licensing restrictions on the use of the VMware
Tools. The whole idea with Player is that you can take a VM (with the VMware
Tools installed) and distribute it however you like.

(Obviously, it's up to you to make sure you are in compliance with the OS
licensing for any VM that you use or distribute.)

Currently Player does not support the installation of the VMware Tools in
virtual machines, since the expectation is that Player will be primarily used for
running VMs created with one of our other products (and thus the Tools will
already be installed). Adding support for Tools installation in Player is a
feature we could consider for a future release, but for the time being it is not
supported.

As far as VMware is concerned, it is not "cheating" to replace the OS in an
existing VM with another OS. It's up to you to make sure you are properly
licensed for whatever OS you install.