Are you sure you deleted your Disk Utility?
Check in your Applications/Utilities folder, which is where it should be...
There's several methods to get your Disk Utility again.
You could retrieve that from your backup of your hard drive. You do have a backup, don't you?
If you have your OS X installer DVD, you should be able to copy that directly from one of the folders on the installer DVD.
Also, Almost every OS X update also updates the Disk Utility - so, you could try downloading your 10.5.8 combined updater, and install that. Here's the link to the updater: http://support.apple.com/kb/DL866
You can install that update (which won't hurt anything in any case, and may have the effect of cleaning up your system, too!), or you can retrieve just the Disk Utility, using an app such as Pacifist - which can do that job very nicely.
I do recommend that you install the combined updater, too. Be prepared to just let it install, as it may take nearly an hour to complete.
ALWAYS restart your Mac just before installing a combined updater, so that your system resources are not in use by other apps. Do NOT try running any other apps while the updater is running, as some will not work, and you may make the updater take even longer before it finishes. The only real problem that might prevent the updater from running, is if your hard drive is almost full. I think the update requires at least 3 GB of space to run.
OHHHHH, noooo! Dear DeltaMac: I do NOT have a backup (d'oh!) dumb me, and since I bought this Mac used I don't have the installer disk, either! I will take your kind advice and use the update link you gave me, and try pacifist, too! Thank you so much! Whew! Thought I was a goner!
An update and a re-installation are two different things. An application on a Mac consists of the binary itself and the resource files which include .nib/.xib files. I would think it's entirely possible an update may not install the binary but may update other stuff instead, which would leave the end user with an unusable application.
I'm not saying you're wrong, I'm just curious if you're sure the update is always a full re-installation of Disk Utility.