*BSD vs Linux for Home Server

I have a few simple needs for my home server - it needs to be stable, functional on older hardware (P4 2GHz with 1 or 2 GB of RAM) and run a few simple applications:

• rtorrent (for... ahem... legitimate torrent requirements)
• irssi - the bestest IRC client (and the one I've spent ages getting a nice config file for)
• screen (for teh awesomeness!)
• SSH - for remote work, and for sshfs so I can rsync and backup data remotely
• and a bit of storage space - 100GB is nice
• nagios - monitoring work sites as required
• DHCP
• DNS

Currently I'm running Ubuntu 10.04.3 LTS on a P4 3GHz USDT HP that has a noisy fan in it and I'm going to migrate back to my Dell P4 2GHz box that I was running before. It has a slower processor, is quiet and reliable. It's also more power efficient than the current one. I've been considering getting my hands on an Atom powered box or the like with very low power requirements for home. After all this server really doesn't have to do a lot or work - it just needs to chug quietly away and provide the basic services I need. So why change?

Well several reasons I guess. Security is the big one. Reliability is the next one. A rolling distribution would be handy too - one with easy, in place, headless upgrades.

Most Linux variants will support the apps I listed, as will FreeBSD and DragonFly BSD, my two preferred BSD variants (even though I've had great success with OpenBSD on my Sun Blade - see earlier posts). I'm thinking FreeBSD may be the option to go with, so I'm playing with it under VMware Player at the moment. DragonFly's HAMMER files system is mighty attractive though, so I'm thinking very carefully about this choice. I'll keep notes on my adventure as it goes forward.