FWIW, I've never seen any reason to have two CD's in a machine, so I have CD-RW drives in most of mine. Places like ComputerGate have CD-RW drives for $30, so saving the CD wear-n-tear seems to be a somewhat moot point.
As far as your disk running slowly, would this be a Win98 system by any chance? If so, you may have a BIOS or setup compatibility that has the drives running in "MS-DOS compatibility mode", which will really slow things down! If that is the case, you can probably fix it and get a significant performance increase.
Right click on My Computer, select Properties, and then the Performance tab. See if there are any warnings displayed about the system. If there's a line that says: "Your system is configured for optimal performance", then you don't have this problem.