Yikes! I can't keep up with all the posts!
Back to leahkat, the OP...my thoughts boil down to, if there isn't anything really wrong with your current set-up, do whatever you can to avoid having to do a needless upgrade...yeah, more recent hardware will be faster (physically) but, if you have workflows you are happy with right now, that will be faster than having to learn new ways of doing things.
You ran Disk Utility and it didn't solve the problem? Sometimes repeated running of the Disk Utility will help. If you have the install disks, you can also boot up from the install DVD and run Disk Utility from DVD. Sometimes that can help (I wouldn't reinstall the OS yet).
You ran Disk Warrior, but it said it couldn't help? I would try alternating between Disk Utility and Disk Warrior once or twice, and see if that made any improvements.
Back in the Classic OS days, I used to run TechTool and had good luck with it repairing drives. You may be able to pick up a copy of TechTool cheap, esp. since it was included as a CD with AppleCare...
Other people may have other disk repair recommendations. Each program works differently, and if one can't help, the other may.
Also, not to get too lengthy...BUT...I would clone your current disk to a new disk (my favorite program is
SuperDuper!), and then start monkeying around with the cloned drive. That way, if something goes wrong, you always have your original drive to get back to. I'm a scaredy cat...and knowing I can always go back to the way things were originally gives me a lot of peace of mind to really try to fix things.
Let me know if you can find out where the funny noise is coming from. I'm assuming you don't have a bird's nest in your Mac...like I said before, there aren't too many moving parts internally.
Finally, you can always upgrade to a "new" used Mac, but I don't think you are there yet (knock on wood). We can go more into that when you have tried more disk repair suggestions.
