The good old cp command did the trick.!

I booted in a Knoppix LiveDVD, mounted only my Arch root partition and the would-be root partition and then ran the command :
cp -pidvxR /old_partition/* /new_partition/
The options mean:
p - preserve file permissions, timestamps etc...
i - prompt before overwrite (just in case).
d - To copy symlinks as symlinks rather than the file they point to.
v - to be verbose about the process.
x - To stay on one filesystem.
-R copy recursively.
Works like a charm.Now I can truly say I will NEVER EVER have to re-install Arch Linux again.!
BTW, don't forget to make appropriate changes to /boot/grub/menu.lst and /etc/fstab after copying..
Another BTW: I could have perhaps run to cp command from within Arch, but it was the special directories like /proc and /dev that had me worried.So I chose a liveCD for the task.