You're using Windows ME, which is really crap (I've experienced it myself).
With 'xp' they mean
Windows XP, which is far better than Windows ME.
I would (also) recommend you to install Windows XP. You can upgrade your Windows ME to XP, but it's better to do a fresh install of Windows XP. (So format your harddisk and reinstall Windows XP). If you don't want to lose the data on your harddisk or/and your don't have the software/drivers that came with your laptop, you might want to upgrade to XP. Note that some drivers don't work with Windows Xp anymore, and you might need to update them (i.E. display drivers).
About the windows scandisk/defragmentation problem:
Because you probably have a lot of programs, like software/drivers that came with your laptop, running in the background reading and writing your harddisk, your harddisk contents are constantly 'changed'. As far as I know this problem would be the same in Windows XP.
For that reason I use a different program for defragmenting:
PerfectDisk 7. It works extremely good and is much faster than the Windows Defrag (NOTE: It's Windows 2000/XP/2003 only, so not for ME!)
