Failed disc check & slow slow boot

Inspiron 1150,  2.8ghz ,  512mb memory, windows xp home, 30gb h.d.    takes 5 minutes to get to desktop from startup.   I ran a disk check from the properties in C: drive, elected to run it on next startup.   It came up but stated could not check the disk, and now this comes up every time I boot the system     HELP!     Dell techs had me run a diagnostics check - it showed hard drive errors but they said this would not keep it from working, that it was a software problem, and refused to replace the hard drive.