When turning on the PC, hold down the DELETE button until the BIOS screen appears. There you can set the Boot Order. Make sure that cd/dvd is selected on a higher level than the harddisk. Now you should be able to boot from the Windows CD.
According to these messages, the Windows install is corrupt. So follow all Install steps, until it asks if you want to repair the current install or install a new install. Choose Repair in that case.
Problems like this could be related to a virus, or a broken harddisk.
If the boot.ini file is corrupt, then it wouldn't know where to find these system files. The messages are actually referring to the files, that are presented by boot.ini. So in this case, the boot.ini should be fine. Otherwise you would see the message "NTLDR not found".