Partition problem in 10.5.2

Hi guys
just tried to partition my hard drive running 10.5.2 prior to running disc partition i had used 59. something gb of 290Gb hard drive. I therefore opted for a 100gb partition and set it going, however when i came back to it latermy machine had crashed and required a power button restart.

This i did however there is no second partition showing, but according to disc utility Macintosh HD is now 160gb how do i revert the drive back to it's previous state. I didn't do a back up before i started doh so have a naffted it

many thanks

Hi guys
Thanks to those of you who read my post, but i have managed to resolve the problem I ran disk repair from the Disc Utility on the start-up disk and the drive is now restored to it original state I should have tried that first

Just as a bit of additional information, I also had to partition the hard drive using the start up CD, for every time i tried to do it within OS X it kept crashing. when i selected partition from start up CD it worked perfect