First of all, here's a better picture of your problem.....
http://nuxx.net/gallery/v/computers/...geViewsIndex=2
....the only thing I could think of is fabricating something from sheet metal or just get some double sided Velcro and mount it on the floor of the case.....OR you could sacrifice a drive bay for one of these....
http://www.directron.com/mis-kit-hd.html
best of luck
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