Can I have two versions of OSX running on same machine?

You are referring to 2006, not 2009 Mac Pro correct? Leopard suceeded Tiger in 2007. All models subsequent to the first 2006 model feature quad core zeon processors.

But, yes. Boot from the Tiger disk, use disk utility to format the second HDD properly (HFS+), install it on the other HDD, and then update to SL. You can choose which HDD to boot to subsequently at startup.

CS2 was a PITA and was the only version I heard of in 2006, folks waited for CS3 to buy Mac Pro models. \

You missed the hundreds of references to lack of Rosetta which drops support for PowerPC code but which has instability, overhead, less efficient, used an extra 2GB RAM and more issues with plugins.

you can run 10.6.8 and have Rosetta, just no Lion or later. You can run 10.6.8 in a VM, not a great way. You'd be better finding a G5 though to run CS1 which is ancient.

2009 had single processor quad-core, the 2006 had dual processor only with two dual-core (also like the G5 which was called "Quad G5") and 2007 brought a dual quad 8-core 3GHz which can be upgraded on a 2006 with 53xx processors.

Upgrade your software, avoid the issues, a system that can run Mountain Lion has to be 2008 3,1 or later and uses a minimum of 10.5.2 or later only. Not Tiger (thankfully). 10.6.8 the recommendation is CS4 btw, not CS3 or earlier.

My Mac Pro has 10.6 and 10.8 installed on two different (internal) disks. I can boot to either one, depending on what I want to do. So YES they are running on the same machine. But not at the same time: I have to reboot to go from one to the other.

johnfrombanchory wrote:

Any tips welcome.

Rosetta is an optional install on Snow Leopard, so be sure to check that box and IMHO also select Quicktime 7.

The hatter wrote:

...Rosetta ... which has instability, overhead, less efficient, used an extra 2GB RAM and more issues with plugins.

Most of that statement is inaccurate, but the amount of inaccuracies is irrelevant if the OP requires Rosetta to run his CS1 suite on his Mac Pro.

OP: My plan is to install an additional hard drive in my Mac Pro (2009 dual Xeon version)

You can't run anything less than 10.5.7 on that system. There was too much confusion over what can or will work with your plans. Adobe recommends CS4 or later and does not support a PowerPC version or even CS3 (though people did) with Snow Leopard.

CS1 was PowerPC

Adobe took the bait and went down a dead end path with Carbon based

Now they are fully onboard with Intel COCOA based code base and left that behind.

CS1 is from the POWERMAC era

johnfrombanchory wrote:

No idea what Rosetta is as I've never used it and I definitely had CS1 working fine under Snow Leopard previously so why wouldn't it work again?

John

Rosetta is the transparent emulation software that allowed Intel Macs to run PowerPC software. It is an optional install in Snow Leopard, so you will need to check that box before you install Snow Leopard.

Then CS1 will function on your Mac in Snow Leopard.

For a brief time, Adobe was offering CS2 (also PowerPC) for download from their site, but realized that it was giving away something of value and stopped that download, unless you acknowledged that you already were a purchaser of that version.

The old "pop the DVD in, hold down Option or Command + C and just do a clean install on your new drive doesn't cut it?

As for SL, it has to be retail, can't be the OEM gray disc from another Mac specific model.

http://pondini.org/OSX/Home.html

The hatter wrote:

As for SL, it has to be retail, can't be the OEM gray disc from another Mac specific model.

I can't tell you how long I've been trawling the internet looking for exactly that answer. Thank you!