Managed to finally copy my data off my file server with no errors and install OpenSolaris 06.2009. Previously I was using an Adaptec AAR-1210SA sata controller as the mainboard pre dates SATA. Unfortunately this card is not supported by OpenSolaris and had to be replaced with a Sunix SATA4000 SATA controller. Out of the box this card does not work with OpenSolaris but if you re-flash the cards BIOS with the base 18.104.22.168 BIOS available here as described at Sun's BigAdmin Portal it seems to work fine.
My file server is an aging Athlon XP 2100 1.7GHz single cored CPU. It took quite a while to install OpenSolaris and boot times are less than impressive. Once it is running it seems fine though. OpenSolaris is a strange beast compared to Linux. Same ideas but implemented differently. Even a simple task such as configuring a static IP address on a network interface is completely different to Arch or Debian Linux. The OpenSolaris Bible has been a great help.
Once the OS was installed I setup my main data zpool. I mainly followed A Home Fileserver using ZFS for this. I copied all my data back and exported my file systems via NFS and mounted them on my Arch workstation. It's difficult to be sure but I think I am taking a performance hit especially on writing. I should have performed some benchmarks before reformatting to compare with the performance figures I am getting now. There are quite a few settings that can be tweaked with ZFS so I may be able to improve the speed a bit. ZFS looks impressive. I have yet to play around with snapshots or volumes though I intend to do so. ZFS's snapshot feature and send and receive commands should make implementing backups fairly simple.
I have also finished configuring Postfix on my mail server. This is the first time I have configured a mail server for anything but basic local delivery. The Postfix web page is a wealth of information.