A new version of vmware workstation has been released (5.5.4).
It addresses several security vulnerabilities including overwriting
host os files, DOS and potential stack corruption.
CVEs: 2007-1337, 2007-1877, 2007-1069, 2007-1876, and 2007-1744.
Download it here:
http://www.vmware.com/download/ws/

Review security issues addressed here:
http://www.vmware.com/support/ws55/doc/releasenotes_ws55.html