Physical Log Size v5 -> v7

Hello, I have a small question concerning the size of the physical log. According to the Online v5 Adm. Guide the size of the physical log should be created from "..is that total disk space allocated to the physical log and the logical log files should equal about 20 percent of all dbspace dedicated to Online. The ratio of logical log space to physical log space should be about 3:1." But the v7.2 Adm. Guide says theat the Physical log size should be calculated from userthreads * (max_log_pages_per_critical_section) * 4 These two calculations give VERY different results on one of our machines (197000KB vs 4340KB). Can anyone help? Thanks, Scott Hanson