These temperatures are very good already...you don't need additional cooling. BTW, are those temps from a thermal probe, or is it read directly from S.M.A.R.T. hard drive monitoring info? (If your hard drive supports temperature monitoring via S.M.A.R.T., then download a program called SpeedFan 4.04 to read it)
With my Maxtor 40GB 7200RPM ATA133 drive, I get internal temps of 29C when it is placed directly in the airflow of the two front case fans in my Lian-Li PC-82, and temps of 40C when it's placed next to the floppy drive. I don't have a thermal probe to compare temps with, but I'm betting the internal monitoring is more accurate.