Sometimes you, or The Exchange Guy, find yourself in the situation where you need to run ESXi on a desktop machine for “testing”. Sometimes, however, things don’t go quite as planned and you find yourself having to do some mucking about to get it working. There’s some good coverage of the CPUIDlimit workaround here. But here’s a rough outline of the options available:

http://communities.vmware.com/message/1136449

During installation:  in the bootloader (booting from CD-ROM), press TAB
go to the “vmkernel.tgz” and add nocheckCPUIDLimit
“mboot.c32 vmkernel.gz nocheckCPUIDLimit —” 
During the normal boot process: press SHIFT O and enter the option nocheckCPUIDLimit

Of course, you’re probably a busy person and don’t want to have to remember to do that each time you reboot. So, post-installation, go to Advanced – VMkernel – Boot and modify the setting accordingly.