Raid5 array failing left and right. Help!

I have been having the issue for the past month with this same tower, while running in a raid5 array, every once in a while a drive will fail. I could see this being very easily solvable if only one drive failed, I could just replace it then. The problem however is that I've replaced two of the drives already, and I'm begining to think that the drives themselves arent what is failing.

Right now my current setup is a 64 bit edition of vista home premium, Ive got 2 gigs of ddr2 800 ram, 4 western digital caviar 160 gig drives, and a 2.4 GHz Intel Q6600. Video card is an 8600 GT, and I am running this all on a P35-DS3R.

The big issue that I have had with this is the fact that this issue is reoccuring all the time, on different drives. So far I've had every single one of my drives label itself as 'failed' at least once. This has even followed me through 3 different full wipes/reinstalls of the operating system. The drive gets labeled as failed on the bios as well. Something that had just recently struck my attention was the fact that I can now get the issue to occur in a repeatable fashion. Seems that whenever I try to install the newest updates MS has out and restart, a drive fails.

To be honest, I would be surprised if this was the OS's fault. I have yet to have any issues with this machine save the raid array issues. If someone could at least point me at what I might be doing wrong, I would be much obliged. Until then, I get to let my computer sit and rebuild parity for another 10 hours.

Are the drives all stacked together? Are the drives staying cool? 4 drives in RAID will need excellent ventilation.

You may want to try western digital's RE (raid edition) drives. They claim these work better.

From their web site:
RAID-specific time limited error recovery - Improves error handling coordination with RAID adapters and prevents drive fallout caused by extended drive error-recovery processes.

Q: What is time-limited error recovery and why do I need it?
A: Desktop drives are designed to protect and recover data, at times pausing for as much as a few minutes to make sure that data is recovered. Inside a RAID system, where the RAID controller handles error recovery, the drive needn't pause for extended periods to recover data. In fact, heroic error recovery attempts can cause a RAID system to drop a drive out of the array. WD RE2 is engineered to prevent hard drive error recovery fallout by limiting the drive's error recovery time. With error recovery factory set to seven seconds, the drive has time to attempt a recovery, allow the RAID controller to log the error, and still stay online.