A quick note about memory requirement: the Zimbra LiveCD will not run on machines with 512MB RAM (the Mailbox service fails to start). I recommend, at minimum, 768MB RAM since you're trying to run Zimbra, X, KDE, and Firefox with three tabs open. If using the VMware Player as I describe above, you can change the memory allocation:
- inside VMware Player by clicking Player, Troubleshoot, Change Memory Allocation
OR - by editing the .vmx file and changing the memsize setting