Hard drives too hot?

[Slow Cheetah]

After taking advantage of some of the hot deals on this forum I'm now up to 4 hard drives. Yesterday when I opened up my case I noticed all of the drives were noticably warm. How do I tell if the HDs are getting too hot? Do you think I'll have a cooling problem with 4 HDs in a stock Antec Sonata?

The four drives are as such from top to bottom: 1) WD Raptor 2) Maxtor Diamondmax 10 3) Maxtor 250GB 4) Maxtor 250 GB

 

[Copper0]

try Speedfan and you'll have a better idea when things are too hot