Vmware Converter does work for almost anything, what you would need to do is cold clone the server…make sure the hardware is on ESX’s compatibility list. This is a free download.
Read page 45 and on cold cloning requirements from this PDF.
One more thing… I suggest, shutting the server down and installing an INTEL Gigabit Ethernet adapter, connecting it to a gig network then, booting with the cold clone cd… it would take hours with a 10/100 ethernet adapter.
Hope this helps!