I wanted to extend the 40Gb to use the whole drive capacity.
I took the new 160Gb disk placed it in a USB external case, connected it to another Windows XP PC and use DISKPART to extend the partition.
DISKPART
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and Settings\Stephen>diskpart
Microsoft DiskPart version 5.1.3565
Copyright (C) 1999-2003 Microsoft Corporation.
On computer: PC-12OCT07
DISKPART> ?
Microsoft DiskPart version 5.1.3565
ADD - Add a mirror to a simple volume.
ACTIVE - Marks the current basic partition as an active boot partition.
ASSIGN - Assign a drive letter or mount point to the selected volume.
BREAK - Break a mirror set.
CLEAN - Clear the configuration information, or all information, off the
disk.
CONVERT - Converts between different disk formats.
CREATE - Create a volume or partition.
DELETE - Delete an object.
DETAIL - Provide details about an object.
EXIT - Exit DiskPart
EXTEND - Extend a volume.
HELP - Prints a list of commands.
IMPORT - Imports a disk group.
LIST - Prints out a list of objects.
INACTIVE - Marks the current basic partition as an inactive partition.
ONLINE - Online a disk that is currently marked as offline.
REM - Does nothing. Used to comment scripts.
REMOVE - Remove a drive letter or mount point assignment.
REPAIR - Repair a RAID-5 volume.
RESCAN - Rescan the computer looking for disks and volumes.
RETAIN - Place a retainer partition under a simple volume.
SELECT - Move the focus to an object.
DISKPART> list
Microsoft DiskPart version 5.1.3565
DISK - Prints out a list of disks.
PARTITION - Prints out a list of partitions on the current disk.
VOLUME - Print a list of volumes.
DISKPART> list disk
Disk ### Status Size Free Dyn Gpt
-------- ---------- ------- ------- --- ---
Disk 0 Online 373 GB 0 B
Disk 5 Online 149 GB 112 GB
DISKPART> select disk 5
Disk 5 is now the selected disk.
DISKPART> list partition
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 Primary 37 GB 32 KB
DISKPART> select partition 1
Partition 1 is now the selected partition.
DISKPART> extend size=112000
DiskPart successfully extended the volume.
DISKPART> list partition
Partition ### Type Size Offset
------------- ---------------- ------- -------
* Partition 1 Primary 147 GB 32 KB
DISKPART> exit
Leaving DiskPart...
C:\Documents and Settings\Stephen>
This site has a good description of DISKPART
http://www.pctoday.com/editorial/article.asp?article=articles/2004/t0203/27t03/27t03.asp&guid=