Ghost speed differerent in AMD & Intel

I make extensive use of an OEM version of Norton Ghost 2003 that came
bundled with a mobo, and I've always noticed a huge difference in
speeds when I make backups on AMD and Intel machines of comparable
configurations : AMD always finishes in a quarter of the time taken by
Intel.

AMD : Athlon XP 2000+ to 2600+ on Asus A7N266, A7N8X and Biostar M7NCG
mobos.
Intel : P4 1.9 to 2.8 GHz on Intel motherboards (fewer machines
tested)
All with 256MB DDR RAM, Seagate 7.2krpm HDD.

Given below are times taken. The figures are only approximate as I
have not kept accurate records and exact hardware configs varied.
However they are not one-off operations - I get these figures
repeatedly.

Basic Win98SE : AMD 1 minute, Intel 4 mins
Win98 + drivers + other software (1GB) : AMD 5 mins, Intel 20 mins
Win98 + WinXP + other software (3.4GB) : AMD 9 mins, Intel 35 mins

I surface-scanned the HDDs and installed the softwares myself. I
always use Ghost in DOS mode by booting from CD so there's no Windows
involved. HD space ample and defrag makes no major difference.

I can't believe that this is mainly due to the difference in CPU
types. I work mostly but not exclusively with AMD computers, and since
I'm less familiar with Intel systems, I'll appreciate suggestions as
to what I'm doing wrong when using the Intel machines.