You can imagine where it goes from here.

Shutdown
<install new/replacement disk>
fdisk
mkswap
umount /boot
dd
e2fsck && resize2fs
mount -o remount,ro /
dd
e2fsck && resize2fs
mount -o remount,rw /
pvcreate
vgextend
pvmove (wait a long long long time for 174 GB, especially with disk read errors, to move)
vgreduce
shutdown
remove old and busted, put new hotness in as primary disk
boot into rescue disk
mount / /usr
grub-install /dev/hda1
ms-sys -m /dev/hda
vi /etc/fstab
shutdown -r now
Party like its 1999 or, [...]