I have had good results with the migration assistant, though I have not gone from tiger -> leopard. Are both on 10.5?
When you pull out the new macbook, it will have a couple prompts. When you get to the "new account" section, you have the option to migrate, which is what I would tryt first. Your only expense is a firewire cable, and the source machine stays untouched should you need to try a different method.
*out of curiosity, what are you using for VMs? Parallels? Fusion?