I believe there are 3rd party "journal" programs for Windows CE (Pocket PC).
There definately is one for Palm (Pocket Journal). I have used this with a
Palm V for a few years now. It does not have a contact "activities" tab, but
if you open PocketJournal and sort journal entries by contacts, all your
journal entries show up under the contact name. It's not a one step process
like Outlook--your contact address, phone, etc. is in the Palm Address Book
and your "activities" are in Pocket Journal. I don't know if Pocket PC is
any better. FWIW--the Palm software is great at synchronization. It can
synch right down to field level in Outlook. Too bad Outlook can't figure out
how to do this between two PC's sharing a .PST file.
There are some other drawbacks to Palm you should consider, too. Like there
is zero multitasking. Seems like no big deal, but everytime you do a "find"
and get a list, if you pick an item there is no filtered list to go back to.
You have to do the "find" all over again. If you are in Address book on a
contact then want to look at a Mobile DB item, the Address Book is closed.
You have to look up the contact again after you're done with Mobile DB.
Supposedly Palm is going to fix this in their newest OS--it is a pretty big
drawback to their OS, I think.
Check around for a Journal program you might be able to test out on your
Pocket PC first--that' s my recommendation. I know I have seen them.