Hi, I recently got a pre-owned iMac with the Snow Leopard 10.6.3 installed on it. It has a user plus guest account. The person who gave it to me doesn't remember the password. I tried booting from the disk that came with the mac to access the disk utility to reinstall the operating system. I tried the option key and also C key at the start up but it took me to login screen instead of the disk utility. I am using a wireless keyboard that came with the mac. I also tried a non-mac USB keyboard and hit option key but it didn't work either. I don't want to invest in USB Mac keyboard without knowing if that would work for me. Please help me to reinstall and use this Mac. Thanks.