I can replace it without any problemss with my friend. I know it runs, Windows Mobile, Windows Phone 7, Android, Meego and Ubuntu (maybe more, not sure). No Maemo, but there is Meego and Ubuntu. Android works better on HD2. It has more RAM and bigger screen. So is it worth it?

It's like asking if I should replace my Bugatti Vyron with a Vauxhall... Call me bias, but d'oh! *slaps forehead*

The number os OS's a phone can run shouldn't be an indicator of how good it is.

And asking a question like that on a forum like this is hardly going to get you an unbiased answer.

It's not an indicator. That's why I also wrote about the hardware. But if it ran only Windows Mobile, I wouldn't even think about it.

i would love to see n900 run windowsmobile 6.5 though.
anyway the choice is yours. htc hd2 ain't bad but never used so i don't whether it's better than n900 or not.

my sister has a hd2, i helped her flash the rom and loaded android on there, works perfect, its actually one of the most smoothest android experience you can have on any phone. you can choose from stock froyo to ones with htc sense, its great. don't get me wrong, i love my n900, but i wouldnt mind having a hd2, both are great because theres so much community support for the phone

I think the best choice os htc desire z. It have a qwerty keyboard, screen is bigger, you can run maps like ovi mapqs what means without data connection. I think it's a good choice.
Kp

not so sure about HTC products tbh. But XDA Dev are a great community

ive owned a HTC Prophet, HTC Charmer, HTC Touch Pro and a HTC Shift. The prophet charmer and touch pro all developed major hardware faults within a year, and windows mobile isnt an operating system, its a plauge that xda have had to spend years slowly nurturing, so ignore that straight out of the box.

HTC shift is different, some issues but i do love it, i think its windows 7 that makes the difference.

The key i think with a device you rely on so much like these is to make sure the primary supported os is going to do the job for you, the other hacked os' are usually great but theres usually something missing in them that sends you back to the origional os, and windows mobile . . .ugh

if youre going htc get an android based one that you can put other secondary os' on