<< can i put one hard drive and one cd rom on the same ide port? and which one should i use as master and slave? would doing this cause any problems >>
Yes. It doesn't really matter, but it's nice to make hard drives master. Only one device can use a controller at a time, so if you want data to go through the CDROM and HD at top speed then stick that CDROM on the second controller.
Normally, a burner gets preferance to prevent coasters, so if you have one hard drive and three CD's, make the HD primary master, make the burner secondary master, and the other two CDROM's slaves.
id make the hd primary master, then the cd-drive i use most as secondary master. place all else slave. only a maximum of four drives on an IDE interface.. if you need more, then you need to get SCSI drives as well and a SCSI controller (they cost more though).