Hello Tolanid,
Your best best is going to be to run ESX / ESXi on VMware Workstation 7 on your laptop. Workstation 7 has ESX/ESXi 4 as a supported guest OS, so you don't have to edit the config files like you used to on Workstation 6.5.
Also, even if you do manage to get ESX/ESXi installed directly on your laptop how will you access your ESX Servers / VM's? You need a machine with the VI Client, so you will need to carry around two laptops if you want to be self sufficient. I hope this helps.
Don't forget to mark this answer "correct" or "helpful" if you found it useful (you'll get points too).
Regards,
Harley Stagner
VCP3, VCP4