Thanks for the replies.
re the source of information - it's from the Bleeping Computer Tutorials: http://www.bleepingcomputer.com/tutorials/...al55.html#spare
- it seems to indicated the best/easiest way to de-fragment is to use a second hard drive rather than use a DeFrag tool.
Quote: "Using a spare hard drive to defragment
Probably the best way to defragment your hard drive, if it is in your budget, is to use a spare hard drive. In order to defrag you would copy all the data off the heavily fragmented drive onto a clean spare drive. You would then delete all data on the fragmented drive, and then restore that data back from the spare drive. This will then copy all the data back to the drive in a clean contiguous manner.
This method will work for any operating system."
I don't think my hard drive is too full; if it is as you say I could simply move larger files.