Having a issue rerooting

[zathus]

ok so last week i decided to unroot my phone to test out if it was root that was making my camcorder glitch out. after some trial and error i found out what was wrong. but.. while unrooting I installed the OTA update. Interesting thing about the OTA update is that non of the update.zip root files work now. keeps saying error. Ive searched about 10,000 threads trying to figer this one out. any advice? just incase your unsure what my question is, I now have the ota update 2.1. I want to reroot my phone but cant figer out how