I have a IDE Hard Drive and DVD Drive sharing the same IDE header. Will the transfer speeds be affected badly?

To express what I mean, my mainboard will be a PC Chips P17G/1333 Motherboard w/ a Pentium D 830 @ 3.6 GHz. There is only one IDE header, to which a Western Digital Caviar SE 320GB IDE hard drive and a AOpen 16X DVD-ROM Chameleon IDE Drive will be connected to. You might ask why I'm not using a SATA Hard Disk; I'm installing Windows XP and don't want to go through the SATA Driver process. (It's confusing.) Please tell me if the transfer speeds of my Hard Disk and DVD Drive will be affected significantly. In case you were wondering, the devices will be connected using a Ultra 20-Inch Round IDE 2-Device Cable.