|Please, please don't try to install a stand-alone 98 OS on that. You're going to have problems finding drivers and the 4 gig of ram will be an initial problem.|
That particular error you're getting means 98 install isn't finding a cdrom. That's because you likely have a SATA cd/dvd drive. The driver it's loading is for IDE/atapi cdroms. Your PC can boot the 98 cd because the bios recognizes the sata drive but 98 doesn't.
It's also likely you have a sata hard drive which 98 won't see either.
You have 2 practical choices--either install 98 in a VM setting within windows 7 or get an older PC from the P-III era and install 98 on that one.