10.4.8 - Six different Macs all with problems since the update...

We run a business which has six different Macs... all relatively new (3 yrs). Typically we run the auto updates, because that's what we're supposed to do, and we experience little if any problems.
This last update (10.4.8) has caused nothing but problems - little system hickups here and there. Programs hang. Strange screen anomolies. Laptop trackpad issues (clicks and selections when none were made). I have to say that if Apple is going the way of the Windows machine I'm not impressed - at all. Consider thoroughly test your updates before releasing them on your loyal client base. Seems like a simple concept.
Is there anything that can be done to limit the impact of the recent update. Backtracking to the last version is not an option, although setting up the system to allow for this will become a part of our workflow in the immediate future.
C Jones
dual 2.0 G5's, 4.5 GB memory, ATI x800 Graphics card Mac OS X (10.4.8)
dual 2.0 G5's, 4.5 GB memory, ATI x800 Graphics card   Mac OS X (10.4.3)

Started having problems with my Imac first power supply (replaced under warranty), then HD/Boot issue. I ran disk repair and was advised by support to try to do an immediate backup (purchase external HD) and reinstall OS from CDs. Although I purchased an external firewire HD that day, my HD failed the next day (unable to backup onto new Glyph in time) so I lost EVERYTHING.
I investigated data recovery options, but just waaay too expensive. So yes, there's nothing like a good backup plan. Lesson learned.
Today (after a nightmarish struggle to get the computer repaired--different issue) I finally got my computer back with a new HD and logic board.
So, I rushed home to start reinstalling OS and software. First installed original OS X Panther disks which incl Garageband, no problems (also set up internet to try to register all software), checked for firmware update (none), ran software updates, rebooted). Then I installed OSX Tiger (ran software update...10.4.8, etc, ), started Garageband new song one track piano (using an M-audio keyboard controller i had hooked up but had not yet installed the software drivers) and it worked! Very cool. everything was time-consuming but seemed to be working fine (and why wouldn't it on a brand new HD with all software installed via CD and all updates recommended by Apple?)
Then, I decided I would next install the GarageBand JamPack CD (before attempting to tackle external HD setup, Pro Tools, synths, etc). So, I saved the "testsong" when closing and received error "Gband unexpectedly quit" and it stopped responding (spinning color wheel). After a few minutes I was able to force quit the application (really didn't think anything of it). Then I rebooted (since it did crash, I did go back and look for a possible software update but said I was up to date).
I tried to install Gband Jam Pack (1) failed about 95% of the way through while I was trying to complete product registration online. Then I rebooted, tried again failed (during which my internet also stopped responding). I had to then reset the wireless router and cable modem, looked for help online and rebooted.
I then ran repair disk permissions (it looked like it did a few updates but I did not see any alarming "errors" flash across the screen). I rebooted and tried to install JamPack again, failed, and rebooted (and looked online for another suggestion).
removed folder: application support/gband/loops/Gband Jampack/ folder into trash then tried to install jampack again, failed, and rebooted.
removed folder again, ran repair disk utility (did not look like it made any updates or report any errors), rebooted. Tried to install again and failed and rebooted, emptied trash and rebooted again.
I am now running repair disk utility one more time (10 solid hours into the software installation process ....my internet just stopped responding again so I apparently have to reset the wireless router again just before trying to send this message). I will run repair one more time, and completely power off computer for a couple of hours while I grab some sleep before work.
But, now I am seeing all these SCARY stories about the 10.4.8 update I just installed?!.
Are these problems related? Can someone please help me? Surely it cannot be this difficult. Thank you!
Imac G5 1.8 1.25 GB RAM   Mac OS X (10.4.8)