In the guest, you’ll want to run NTP and not use the VMware tools time sync. It seems to work better. Also, you might also considering Ubuntu 7.1.0 instead as with ESX 3.5, VMware Server 2.0, and Workstation 6.0, it has a VMI option, so that you can run a paravirtualized kernel and get up to 30% better performance. It also doesn’t have the LSILogic scsi driver bug that everyone seems to run into.