I needed to run a demo for some customers, but our lab environment is going through a relocation process to a new datacenter so I had issues with both VLANs and SAN connectivity that wasn't fully available as needed.
Instead I decided to try to install ESX 4.0U1 on a Lenovo Thinkpad T500 (dual core 2.8 GHz,, 4GB ram). It comes with an Intel based nic and Intel based SATA controller so I thought it should have a fair chance on being able to run ESX.
I booted the ESX cd and the installation process would only run in text mode, but that's not a big deal. After entering text mode I answered all the questions the same way as if it was a real server and I did not need to load any extra drivers.
After finishing the installation steps I successfully started up ESX, configured it, and setup a few VMs. It worked out quite well. The io is quite limited when running your VMs from a single SATA disk, but it can easily run a handful (low load) VMs. As always, the cpu is not the limiting factor: RAM and storage performance are, and I did get way high disk latency while doing installation on multiple VMs simultaneously (40-50ms). Other than that, the VMs were running quite well once installation was finished.
The system was running very stable, but I had a few PSODs during shutdown of ESX. I didn't look more deeply into these (during ESX shutdown) PSODs as this system is a 100% unsupported config.