Yes, you may have done more harm than good, but all is not lost. Armed with what your backup status is, I'll make the following suggestion:
1. Get four things: Tiger retail, Alsoft Disk Warrior 3.0.3, Prosoft Data Rescue, and an external Firewire hard drive bigger than your current hard drive.
2. Boot off Tiger retail and go to the Utilities menu after selecting the language selection.
3. Select Disk Utility and erase and partition the external hard drive. Make sure at least 10 GB exist in one partition, while more room exists in the second partition than the internal hard drive. Format both HFS+ Journalled.
4. Install Tiger on the 10 GB partition.
5. Boot off the external hard drive using the Startup Manager:
http://docs.info.apple.com/article.html?artnum=106178
6. Tell us if the internal hard drive is visible at all, and if it is, backup what you haven't already, and remove nonessential files you've created from the internal drive using my FAQ:
http://www.macmaps.com/safetodeleteormove.html
And use this to find files you created that are too large:
http://discussions.apple.com/thread.jspa?threadID=122973&tstart=20
If it isn't, go to step 7.
7. Boot off Prosoft Data Rescue and attempt to recover information to the larger partition.
8. If the information looks usable after booting back into the 10 GB partition, back it up to where you had your original backup first.
9. If the information does not look usable, try running Alsoft Disk Warrior on the internal machine. If Disk Warrior baulks, you may need to go to a data recovery firm to recover what you haven't already backed up. And in the future always remember to never let your hard drive get less than 10 GB full.
10. If Disk Warrior appears to be successful, boot off the internal drive and see if you can remove nonessential files as I mentioned on step 6.
Your final step is to always keep a frequent backup of your data as my FAQ explains:
http://www.macmaps.com/backup.html
Good luck!
