You should be able to go to Gateway's web site and download the required driver for that DVD/CD drive. As an alternative, you could always buy an external DVD/CD drive for around $30 and use that.
Gateway DX-4720-03, Desktop
This might be a little long and complicated. I'll try to be brief. A heinous virus evaded my anti-virus software and wreaked havoc. Corrupted registry and various files. I had backed up my Vista Home system to a external HD for saftey. Decided to to a repair/re-install using disks I had made after purchase. None came with my system. Everything was going fine until the re-install asked for the next disk. Not good. I didn't have them. Only 1 disk and a driver disk. I did not lose them. Anyway now my hard drive has been wiped in preparation for the re-install. When I attempted to transfer files from my back-up external drive it self-destructed like on Mission Impossible. Now everything was gone.I have nothing to re-install and a partially erased/formatted hard drive. Brought it to Best Buy and they said the hard drive is empty. Ok got a copy of Vista with serial number to install. Booted off install disk. So far so good. Files get loaded. When it comes to the actual install screen and I hit Install I get a pop-up that says "A required CD/DVD device driver is missing. If you have a floppy disk, CD, DVD, or USB flash drive please insert now". I have tried everything from downloading drivers from the Gateway site to changing SATA to ATAPI and I can't get by that pop-up. Any ideas would be greatly appreciated. thanks