Out of interest, the DHD will not be getting Ice Cream Sandwich, so there wouldn't really be any more updates available for your phone - to me that would seem to make more sense to be rooted and be able to put custom ROM's on your phone... I currently have ICS on my DHD. If you are worried about installing custom ROM's, we would be happy to help you out but, if it's really not for you, then no worries!
there will be an update for the inspire that brings it up to sense 3.0. pretty exciting if you are unrooted and wanting that sense version,along with att bloatware
Before you go ahead and use that RUU, let me get the go ahead from Scotty - he's in the US and has an Inspire which, although it is the same as a Desire HD,
may have differences - always best to double check!!
As for ICS on our phones... there are some custom ROM's which are very stable and full of features however, as ICS is not being released for our phones, there are some issues (I believe most ICS ROM's for the DHD do not yet have a working video camera) - this is as source code has not been released (in the form of an OTA update.
Hang fire... I'm sure Scotty will chime in soon to give you the go-ahead
as long as the inspires root method involved a superCID,then that RUU will work fine. if youre not superCIDed,the update will just fail,it wont do any harm to your phone.
also i agree with all the comments D-U-R-X made... we can certainly help you learn to flash roms if you wish. once you get the hang of it,its alot of fun. im currently running jelly bean on my inspire :smokingsomb:
its also a very good idea to not unroot completely. leave superCID and s-off so you can easily run different RUUs f you want,and you will be able to easily re-root in the future if you decide to. neither of those things will affect the normal operation of the phone running completely stock software.
ive run the ruu durx mentioned on my inspire and it worked just fine. its a very nice rom,with no bloat. the only disadvantage would be that you will not recieve updates from ATT. in theory,you will continue to get updates from HTC,but i dont know for sure on that.
if you wish to be ATT stock the ruu you need is this one:
Shipped ROMs
if you use it,youll continue to recieve ATTs bloated updates
as far as directions,just download it,and run the utility as administrator if possible on your PC(if not just run it). enable usb debugging on the phone,and plug it in when the utility tells you to.
if it fails for one reason or another,i can upload a slightly different version that you can install from your sd card in the phone.