Mike's boxes are running ext2 unless he upgraded them when I wasn't looking. There have been similar reports of ReiserFS killing PostgreSQL performance, too, so I've shied away from it. Both RDBMS's really want as little operating system interference with disk reads and writes as possible...
My home desktop system is running ext3 and thus far I've had no problems with it. I've got another box running PG and Oracle, though, and that box runs ext2 so I've made no effort to benchmark ext3 performance with either Oracle or PG.
As far as running several instances of AOLserver limited to 10 threads each, you may want to re-benchmark under Linux since threading and multiprocessing are areas where various Unices are extremely different in their implementation.
