i agree go the xda route.
software is so redily available and supported.
good bit of tweaking etc. sat nav runs great on em. great games, business apps etc.
i went from 9500 to spv m2000/xda2/etc (the one with slide out keyboard) and i love it. especially as i use free gprs on o2 pay and go sim and the internet browsing is great! really fast loads etc, and it prob is my main use. and no other web browser has been as quick as much as i hate to say it the microsoft one.
just get a 1gb card or more (if model supports it) and ul be well away.
to give you an idea of what i have built into one device
3.video player (can get 4 compressed but great quality full length movies on to my card no probs)
4. sat nav
6. web device using wifi or gprs
7. self defence weapon (its heavy)
9.a backup of all my important work files incase of any severe crash at work
10. a games machine
11. a remote control should i loose my tv one.
im sure theres more and even more thats relevant to the indevidual owner.
i wnt be getting rid of mine well untill the new xda exec/spv m5000but thats only for desighn reasons, ie i like the keyboard layout and the ability to pivot screen to protect itself etc, and rest assured ill pop me mem card in and off i go so keep an eye out for mine in the clasifieds in few months lol, albeit with a dent in the bottom right corner where i dropped it off 1st floor balcony and it lived! with just a tiny battle scar and i mean a tiny one. wot a proper hard ba***rd