Welcome to the CentOS fora. Reading FAQ & Readme First
is recommended for new users.
I have to recover / reset root password. I do not have the 5.3 cd , can I boot with...
You don't need any CD or other bootable media. See TipsAndTricks/ResetRootPassword
After recovering the password you should immediately update to the current release 5.6. 5.3 is seriously
obsolete and has numerous known bugs and security issues that have been fixed in subsequent updates. Obsolete releases are not supported, nor is it advisable to be running them. See the CentOS 5.6 Release Notes
Section 4 for details on the recommended update procedure. By not updating you are implicitly accepting that you will live with numerous bugs and security issues (and associated known exploits) that have subsequently been fixed.