How to install a 64bit OS as a virtual system? First, ensure that you own a 64bit CPU with 64bit host OS (computer properties). Then run Securable and VMWare Guest Check to confirm you can run 64 bit OS, so, to known your system is Virtualization (VT) capable.
Now you may come to a error like this one: "Software virtualization is incompatible with long mode on this platform. Disabling long mode. Without long mode support, the virtual machine will not be able to run 64 bit code. For more details see http://vmware.com/info?id=152."
This means that even though you may have VT, it is most likely, disabled.
If you're not sure if you have VT and/or it is enabled you should burn vt.iso and boot it, since the applications above will only tell you if your CPU is 64bit and VT exists somehow. This checker will tell you exactly what is the state of VT, which will be one of the following.