It "appears" that you have a square taper crank, with a cartridge type BB-
http://techdocs.shimano.com/media/te...9830612830.pdf
http://techdocs.shimano.com/media/te...9830608719.pdf

ASSuming the BB is bad, you'd need the BB removal tool, plus a crank removal tool, so you're talking about $40?? worth of tools.

http://www.parktool.com/repair/readhowto.asp?id=94
http://www.parktool.com/repair/readhowto.asp?id=103

Make sure it's not the crank arm that is loose on the spindle instead of the BB. Tightening a bolt is much less expensive. Extended use with a loose crank can ruin the crank & BB.