*As I type this*, I'm going through pretty much the same thing with my main server. Here's how I'm setting mine up:
4 identical physical disks (4 x 320GB SATA)
3 RAID arrays, across all 4 disks:
Small RAID1 (200MB)
... logical partition
...... /boot (ext3)
Small-ish RAID0 (5GB)
... LVM volume group
...... swap
...... /tmp (reiserfs)
Big-ass RAID5 (the rest of the space)
... LVM volume group
...... / (reiserfs)
...... /home (reiserfs)
...... /music (jfs)
...... /photo (jfs)
...... /video (jfs)
(the latter 3 possibly on the same logical volume)
So, the idea is, simple mirroring for the boot partition, simple striping for the "don't care if they die, but need the speed" partitions, and RAID5 for general use. Within the RAID5, partitions with smaller files will be reiserfs (reiser3), and larger (media) files will go on JFS. My reason for this was based on
this benchmark test and one other I've lost the link to, where the conclusions were: reiser for small files / general use, xfs for the absolute fastest write speeds with larger files, and jfs for the fastest read speeds with larger files. The write performance of jfs isn't much lower than xfs, certainly not so low as to trade off read speed for my media.
I recognize a couple anecdotal benchmarks don't prove one or the other is better, but it's enough for me to make my decision.
Back to the adventure (on install CD 3 of 4 now...)