Rooting Methods .
Froyo 2.2 (Pre KD1)
z4root download for Android - Softpedia
Install Instructions :Install apk and root it .Easy as 123
Froyo 2.2.2 (KD1 and above)
Follow the instructions .
Click Root button.
Needs PC with working USB connection
Gingerbread 2.3.4 (KP1)
Depends on the chosen method
Check the threads for info
How to root after gingerbread 2.3.4 update
Easy way to root and Stock Rom without Gingerbread BootLoader All about Samsung Galaxy 551 and more