go here just to section 5
[Guide]Installing A Rom/cwm Recovery/root/or Going Back To Stock. - RootzWiki
Download ClockworkMod Recovery - used to replace factory default recovery program
and Download "su-2.3.6.1.x.zip" to be put on sd card to root.
do steps 2-5 unless you need samsung drivers then do 1 after downloading
do step 6 except use the "cwm-recovery-ALL" file you downloaded instead of the "CWM3_Voodoo.tar.md5" file it states.
then step 7, skip step 8, and finish by doing all of steps 9-14.
I had updated firmware from samsung site to 2.3.4 I500, found this in the rootzwiki and processed only steps needed and was able to root from stock. Just need to use the cwm recovery instead of default recovery.
should see the superuser icon, install busybox and now i am currently using titanium backup to restore all from the froyo 2.2.1 version. thus is why i giving info specs of phone that I can remember.
site for uscellular 2.3.4 firmware i used is
Samsung
click software option to see the software.
this also was the default samsung drivers i needed to instal 2.3.4 and same ones that are needed and don't need to be installed for using odin.