Install iLife on 2nd hand MAC Pro running 10.7.5

Question

Hi, please forgive my ignorance, as I'm not at all tech savvy.
I've found a few threads which come close-ish to what I'm looking for, but I'm feeling a little timid and uncertain about proceeding, so I do hope some kind person can help me understand what I need to do.
The situation is - after almost 7 years, (and three hard drives!) my iMAC has yet again given up the ghost.
My husband has come home with a second hand Mac Pro, purchased refurbished, as is, from his place of work.
This is the machine I'm currently working on, having just got it all set up and net connected.
The issue is, I desperately need to have access to my iLife software, especially iPhoto, and iDVD, as I am up against a tight schedule to produce a slide show tribute for a funeral service a day an a half from now.
The Pro does not have any of these applications installed.
It was sold to us without any installation discs - I assume because it came from an office where a large number of machines would have been running on a network.
I thought, no probolem, I'll just get into the app store and pay for the downloads.
Unfortunately, the available versions require a later version of the OS.
The iMAC I owned prior - the one that just failed on me - originally came bundled with Tiger, and included the iLife apps.
I later purchased and upgraded to Snow Leopard.
I still have my tiger and Snow Leopard discs.
Is it possible to safely install my iLife applications from somewhere on my older licensed install discs, without interfering with the OS on the new (old, but new to me) MAC Pro?
If so, how do I go about this?
I'm sorry to ask such basic level questions. I think I can do this, but my experience levels are not much past total newbie, and I'm worried about messing something up and being left with no functioning machine again, right at a time when I desperately need everything working smoothly.
Thanks in anticipation of your help.

Answer 1

Further to the above.
After a bit of poking about, I now believe iLife may in fact have been pre-installed on the iMAC and therefore not on the install discs.
I have no problems buying new versions, if only they were compatible with my curret OS.
Likewise, I'd be happy to buy the Lion OS, or any later version comapible with this Pro, just to have a valid copy.
ALso, so that I have reinstall capability if the system goes down.
Problem is, I need the applications now, and I don't know whether any stores in my area would be open tomorrow and able to sell me the discs. I haven't really got the time for the 2 - 3 hur round trip to get to the nearest vendor that just might be open. If I had a few days up my sleeve, it wouldn't be an issue, but I have to make this slide show and create a playable DVD of it within the next 24 hours.