If you have a bootloop (samsung logo looping), it is because you messed up the rooting procedure. I had this problem when I tried to root a relative's Ace.
Since you've tried factory reset and it doesn't work, enter recovery mode and do factory reset. (recovery mode: press and hold volume down + power button for 15 seconds, navigate up/down by volume button and power button to select). Reboot and see if it fixes the issue.
If it does not, there are two options: flash CWM from recovery (here's the CWM zip file to flash from stock recovery), then reboot to CWM and install a custom ROM. This is what I did, as I wanted to load CM7 anyway.
If you want stock, download Odin, get stock firmware from sammobile.com or XDA forums (look for Developmet section under your device specific forum) and flash it.