I've been running WHS for over 2 years on a Dell PowerEdge server without any problems, apart from an unfortunate experience with the WHS version of Avast. The server runs 2 mirrored drives off a Dell RAID card, and 3 months out of warranty, this card has died. It will of course take a few days to sort out a replacement, so no WHS. And please no lectures about this not being the correct way to run WHS - I happened to have the Dell server spare, which had been intended to run MS Server 2003.
I store all of my business data on the server and have been regularly backing up to a couple of external USB drives - one connected to the server which alternates with another drive that is kept offsite. So, not knowing quite how the backup works, I plug this drive into my desktop PC.
And voila, everything is accessible through a series of folders which are named with the backup date. So not only do I have the most recent backup, I can also access older stuff that's since been deleted or changed.
So a big tick to Microsoft - thanks for such a simple but effective backup solution. If only I could schedule the backups automatically...