Photo backup program?

I am looking for a good backup program for my photo data. There are gazillion backup products out there and I was hoping to hear about a choice or two that are working well for people here.

Things I'm looking for:

o Runs unattended
o I only care about back up from one hard disk to another

o The backup data format is just standard files in a file system. So, if I want to retrieve a file from the backup drive, I can just browse to it and copy it.

o Backup destination can be another drive in the same computer or a drive elsewhere on the home network

o Has some sort of simple versioning so it can do a backup, but still protects me from accidental deletes for a few days

o My computer doesn't have to be logged in for it to run (e.g. it can run as a system service)

o Gets out of the way while I'm using the computer (no noticeable performance impact while I'm doing other things on the computer)

o I'm only concerned about data files. Most of my data to backup is images, but I may also want to add a few other types of documents to the backup. I am not trying to backup whole disk images or programs.

o Handles incremental backups efficiently (e.g. it doesn't take 4 hours to backup the 1GB of stuff that has changed in my 400GB library).

o I can tell it exactly what I want backed-up. For example, I want all files in my photo hierarchy, except not the Adobe Bridge cache files.

o Has a way to tell me when something has gone wrong (backup drive full, network disk drive unreachable, drive errors, etc...).
o I currently have about 400GB of image data (most of which never changes).
o Must be compatible with both XP and Vista.

I'm willing to pay for a program that does this well. I presume there should be something in the $50-$100 range, but I'd consider more than that if it was uniquely capable.

A friend at work recommended Memeo, but I haven't looked into it yet to see how well it meets these objectives.

Any ideas? What do you all use now?

I am currently using a giant xcopy batch file that runs as a scheduled task and I definitely need something more capable and more robust. Thanks in advance for any ideas you can provide.