HDD temperature concerns

I've recently bought a WD 320GB harddrive. this is my fourth so far. I have never had overheating problems with any of my drives so far despite using no ventilation whatsoever. However, I've become cautious. I installed the drive and began copying files onto it.

My harddrives are a WD 40GB where my OS is, a WD80 GB where my page file is, a Maxtor 160GB and this last addition - the WD 320 GB.

I installed HDDTemperature 1.4 and began moving about 10GB from the Maxtor to the new drive.

At the end of the process the Maxtor off which I had copied the files was up to 49 Celsius and the WD to which I had copied them was up to 53. Should I be concerned? I have mounted a makeshift fan behind the drives but judging by the numbers it hardly seems to be doing any ventilation at all. It's a case fan. Should I start considering buying a HDD fan?

EDIT: Might I add the temperature outside is VERY high, over 40 degrees celsius, we've even had power generators go down cause of it.

 

I can now report the final values on my drives as they're idle. Wether I make the fan blow directly onto the case or keep the room completly closed for max heat, the drive temperatores don't seem to change.

WD 40GB - does not support temperature reading
WD 80GB - 43-44 C
Maxtor 160GB - 49, occasionally 50 C
WD 320GB - 53 C

I have yet to test how their temperature changes when they're being used forl ong periodes of time.

 

I did a major revamp of my HDD's layout. I did as much as possible to rearrange them so there can be more room. The WD320 and WD80 temp droppes by one degree. I will not be able to cool them any more than this. Are the temperatures still critical?