Hi,
Here is a good site I use for my ipaq (210) accessories. The link below is for your model. You can at least get some good ideas there.
Ipaq 110 Accessories : (5 Star Rating) Google Checkout available.
regarding your metal case, the one they have shows the metal case with the plastic see through cover I think is the closest hard case you will find to the rhinoskin one. I have one from Boxwave (same exact thing for the 210). I used to have a nice rhinoskin for my X5 and these are not fully enclose but I like it a lot.
I am very happy with my traditional PDA. I would imagine that someday down the road, I would be using the smartphone, but right now, I have no need for one.
Here is also a link for the HP handheld user forum. You may find some help here as well if you experience any issues. You are probably already aware of this site though since you are a long timer ipaq user.
Business support forums - handhelds - iPaq