I don't sort my images. 

Instead, I file them in this structure ...

My 'CreativeLibrary' folder has several 'sub root' folders:
Upload, WiP, a folder for each scanner,
and a folder for each camera (both film or digital). 

The camera folders have a folder for each year: e.g. 2003, 2004, ...

within each of those 'annual' folders, I have a folder for each session
which is named in the form 'yyyy mm dd location or event name' ...
e.g. '2003 08 02 Pennsic XXXII starting'. 

Those files are on a mirrored drive (RAID 0+1) and currently aggregate
close to 10GBy in 7,700 files. 

BTW, , my music files amount to 5,600 music tracks which is more
than 50 GBy and have outgrown my desktop RAID array -- I will be
building a new desktop PC ... soon ... I think. 

In addition, on about a monthly cycle, I copy all of my files (images,
eMail, projects, ... ) onto 2 external USB HDD.  The latest completed
backup set has close to 70,000 files and occupies almost 30 GBy on
those external USB HDD. 

In the past, I had backed up my files by using WinZip for each major
area: creative, music, eMail, projects, ... and then splitting the resulting
ZIP archives into segments that were smaller than 700 MBy and writing
those files to CD-R disks -- that process included generating MD5
checksum values for each original ZIP file, as well as for each split ZIP
file (each part being smaller than 700MBy) verification while writing the
CDs, verification of the MD5 checksums on the resulting CDs and file by
file verification of the CD-R content -- i.e. ensuring that the CDs were
readable ... BTW, everything was written and verified onto 2 identical CDs. 

Now it's a lot easier to copy to large external HDD -- faster, too. 

Keep in mind that I have all of my essential data in 3 places (3 copies):
desktop RAID array, and also 2 external USB HDD. 

--
Martin