VMWare Workstation 4.5.2
Nice review on VMWare version 4.5.2 which introduced 64-bit support on AMD and Intel 64-bit processors. This covers Windows 2003 Server, Red Hat Enterprise and SUSE Linux Enterprise 64-bit releases.
Read it at the Jem Report.
I have tooled with VMWare for several years now and have always found it valuable whether running it on Windows for running Linux flavors in virtual machines or vice versa on Linux running Windows.