clone a disk by dd, but OS still remember its old size

[patrick at fany.info]

Hi,

I try to duplicate my xp and FC3 to a larger disk, I try

0) use fdisk to partition new disk(hdb)
1) dd if=/dev/hda1 of=/dev/hdb1 bs=32256 (for XP)
2) dd if=/dev/hda2 of=/dev/hdb2 bs=32256 (for /boot)
3) dd if=/dev/hda3 of=/dev/hdb3 bs=32256 (for LVM, and / is included)

I reinstall grub after everything is finished. Everything works properly, except...

"from the df and windows explorer, I found both OS still remember their
old partition's size".  I think partition resize tool like QTparted can help me, but
it also tells me the partition table is correct, I can do nothing about it.

What can I do on XP to make it aware the new space?

Any input would be appreciated.

Patrick