With DriveSnapShot - you would still need to get involved in some scripting if you wanted automated backups - so that may rule it out for you.
I'm not sure if Windows Backups uses volume shadow or not by default, but again if I suppose you could script it to if needed.
backup-for-workgroups.com may be good as it can automatically backup and can use volume shadow too - Like I said before I've not used this, but others on this board have said it is good - you can probably get it (and lot more) from
http://www.servertastic.com/store/
If you had 3 HDDs in your 1U server you can still have RAID1 over two and use the third HDD for backups etc.