Whilst trying to work out how much space files were taking on a disc. I came across two neat tools, firstly:
du -sh drs0tim
Tells you the size of the directory drs0tim in human readable form, if you drop the s option it tells you the size of every subdirectory in drs0tim as well.
There is also a nifty graphical tool called Baobab for GNOME. http://www.marzocca.net/linux/baobab.html