I was doing research on the known issues which need to be taken care while upgrading or migrating to SQL 2005 64-bit on Windows 64-bit Server (Physical or VMWare Virutal Machines on ESX Servers)
Below is the compilation, feel free to comment on anything missed or anything wrong by writing your comments, I will update the document.
Disclaimer:
1. Most the points were taken from forums/blogs posted by people who were facing these issues, Please test it yourselves to confirm/reproduce these issues.
2. Issues faced are as-of-today, May be corresponding ISV's would have released patches for them now or soon!