VMWare Licensing question for ESXI and Convertor

I allways get confused with Licensing. It used to be so simple but not MS and VMware I just get confused.

Here is what I am wanting to do... Without spending any money :)

Use VMware convertor to convert a physical machine to a virtyual machine on an ESXI host.

Now Converter is free / ESXI is free but can I do this or will there be an issue at a certain stage that I will need a license for?

If people know an alternative to get to the same end result I would be keen to hear that also.

many thanks

Edit: Only 2 Win 2k3 machines so not too concerned if this is manual process involved.