Optimum RAID Configuration - IIS

We are planning to purchase a number of PE1750 systems to expand our web farm.

The web farm systems run Windows 2000 /IIS 5.x supporting a number of web sites behind a load balancer.

Most of the standard web site data is stored locally while some virtuals point to a central UNC path.  The sites are dynamic, and most read/writes will be calling ASP pages, and logging OS and IIS.

The current servers are configured with three 18GB supporting RAID5 for the OS and data partitions.  However, we've heard RAID1 would be a better choice for both read and write.  Therefore, to support the current disk requirement, we would purchase two 36GB disks and use RADI1 for the OS and data partitions.  Can anyone tell me which configuration is better (RAID1 or RAID5) and why?

Thanks,
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T