Depending on how "Vista Compatible" the cloning app you use is will determine how much you need to do to effect the change.
Some apps will clone the partition and auto-fix the BCD (the BCD contains UIDs describing the old HDD and so a clone of it will be describing a different HDD to the new location)
Do you have a bootable MS Vista DVD ? If not, start by downloading a repair disk from
here and checking it's OK before you start. Keep it handy in case it's needed.
Copy your old Vista to the new HDD, remove the old HDD and put the new one in its place at the top of the BIOS HDD boot sequence.
Try booting it.
If you're lucky and your cloning app has fixed the BCD, you should need no more action.
If not,
boot the Vista DVD (or repair disk CD), select "repair your computer" then "startup repair"
Do the above (green) line three times.
You should now be able to boot into Vista without the DVD.
If there is no XP option in the boot menu
EasyBCD 2.0
"add new entry"
Windows tab
select XP from the dropdown
let it auto-configure
don't change the drive allocation