Best bet is he's missing something like SATA drivers which is why its not booting off the hard drive.
As to booting off a win 98 backup disk, thats doing it the hard way.
Booting off the XP cd is so much easier and faster, and has all the old 98 tools also, just need to know where they are hidden. 
SATA drivers are on the XP install. You didn't read the thread. He was having problems with an install and the partitioning, hence the win98 boot and FDISK, he was using the XP disk to boot.
Win98 is the "EASIEST" cure all for install problems and partitions. The "hard way" lets see, boot, FDISK partition, create partition time involved 3 to 4 mins added to install.