i use it as my diary and contacts etc away from home, spreadsheets. Email and web. Also its better having a pda to do the job of a pda rather than have a phone make a mees of trying to di it Then i have a nice small phone that fits in my pocket.
I've been using the 5450 since it came out having had the 3650 before. If you're looking to upgrade then the 5550 will certainly please you, especially with pocketpc (or windows mobile as it is now called) 2003.
Do you really need wifi though? If not you might look at the 2000 series or the new 4000 series.
aha! yeah I have a wireless network at home for the whole family and my laptop is also wireless. I must admit its nice sitting on the loo or in teh bath while still surfing on the ipaq!