Why install VMWARE Tools?
Improved display support with SVGA driver
Cut and paste from host onto the VMWare guest
Automation of guest operating system commands
Sync time
Shrinking disk space
Startup and shutdown scripts

In order to install VMWARE tools on Debian, you will need to make sure you have the package “linux-headers-[kernel version]” installed.

If not, you will get a prompt during the configuration asking for the path of the C header files.

To find the version of your kernel, type in:
uname -a

It should say something like Linux infomine 2.6.26-2-amd64 (with your current CPU architecture at the end)

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NOTE: Do this at your own risk. If you put the wrong version of the kernel header files, things will break.
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After identifying what kernel you are using, then add the linux header files
apt-get install linux-headers-[kernel version]
For instance,  apt-get install linux-headers-2.6.26-2-amd64

Then follow the Vmware documentation on installing VMWARE Tools:
http://www.vmware.com/support/gsx3/doc/tools_install_lin_gsx.html