It is not necessary to install Tiger before installing Leopard.
Leopard is a complete OS and does not require any specific version of OS X to be installed prior to your installation. That said, if you have a copy of OS X currently installed on your machine, it will be upgraded to Leopard.
If you are currently running OS X 10.2.x, that's fine. 10.5 will be installed without a problem.
Any programs that you currently have installed will remain in place. The Tiger installer will deal with them and move the required stuff around so that you can continue to use them once the install has finished.
In the event that either of the two applications mentioned, do not run correctly, just reinstall.
P
Well, I better get Tiger installed before Leopard comes a callin'!
Question - I'll install some software upgrades, drivers etc. which I've already covered, but some like Microsoft office, Quark, etc. which I'm not upgrading... will I need to reinstall these existing programs?
Thanks all!

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