YOU AREN'T OVERREACTING AT ALL!!!
I got my PowerBook in June, and the OS has NEVER frozen. I wouldn't be extremely worried, but I would advise checking to see if it's something particular causing the problem. Also, get all updates, repair permissions, and run the maintenance scripts. Instructions for the last two follow.
1. Repair Permissions: Open Disk Utility in your \Applications\Utilities directory. Select your HD and choose "Repair Disk Permissions." This is the most common/effective troubleshooting step.
2. Maintenance Scripts: Open Terminal also in the Utilities folder. Type "sudo periodic daily" without quotes and enter your Admin password at the prompt. Then repeat twice first substituting "weekly" then "monthly" for "daily." These scripts should run automatically but only do if your computer is on from about 3 to 5 AM. They clear junk, rotate logs and other things, make some new logs, and do other stuff I really can't identify.
After all of this restart.