Seeing entire 20GB hard drive

I am running Windows 98 SE on an NCR 3259 PC (Pentium 133MHz). I have a 20GB hard drive which was partitioned using Windows 3.11 which did not have large drive support. I have multiple partitions of about 2GB each. After upgrading to Windows 95 and then 98, can I have 98 see the entire 20GB as one partition? Can I upgrade from FAT to FAT32? Can I do this without formatting the hard drive and copying files back to the hard drive?