XP SP2 doesn’t see whole hard drive

I have 2.8 CPU with ywo 160 GB hard drives only the OS sees them as 137 GB. I have tried using data lifeguard from WD and it requires you to only work on the slave HD and then switch OS to do it again on the other. I now show 2 CPUs,2Primary IDEs, 2 Secondary IDEs, etc. There has to be a better way. I have xp Pro loaded with SP2 added. I didn’t load SP1, MS site says the patched in SP1 are in SP2 and SP1 was supposed to correct this.