Rooting the HTC Desire.
I’m posting this as a couple of folks I know have asked for a step-by-step that wasn’t as complicated or esoteric as most. I also won’t fill it with threats and warnings but a simple disclaimer up front: By following this procedure you will almost certainly void your device’s warranty. The chances you will end up bricking (damage beyond repair) your phone are slim but non-zero, so please proceed on that basis. Also, if all goes well you will only need the information below. If you have problems you will end up wishing you had done a lot more research. Your choice if you want to do that up-front or not, depending on how much of an “it’ll be fine” kind of guy you are. I know I just gender-stereotyped, but hey.
This is a very quick & dirty guide (in terms of needing tidying up for grammar and style) – but it does represent the entire procedure that I pulled from various other resources and actually doing it twice in quick succession on two different devices. I also had some nice pictures and videos but don’t ask – there was a little incident with sd-ext involving the wrong SD card. It’s not like my credibility will suffer with that admission. 
What is missing from the guide is everything that I take for granted, what I call common-sense but may not be universally accepted as such. Things like (this is not a full list): make sure your battery is charged (phone & laptop), (readers in countries with dodgy utility power – i.e. India – make sure you’re protected from a power surge or outage during this procedure). Make sure the USB cable you’re using isn’t full of holes. Don’t pull the cable mid-flash. Make sure you have as many logically ordered backups as possible. Manual (copy/paste) as well as Titanium / Nandroid. Use Jan Berkel’s SMS Backup + to back up your texts and call logs to gmail OTA.
Here it is, I’ll polish it when I’m not falling asleep:
Read and understand the glossary: http://bit.ly/9HtICk
Download unrevoked package: http://unrevoked.com/#desire
Download HBOOT drivers: http://unrevoked.com/rootwiki/doku.php/public/windows_hboot_driver_install
Download HTC Sync: http://www.htc.com/uk/SupportViewNews.aspx?dl_id=1073&news_id=918
Download the ROM you want. In this first pass I used redux 1.2 https://sites.google.com/site/romredux/rom-downloads
Install procedure:
Finished
uninstall everything that can and will sync the phone with the computer (like doubletwist) to be safe. REBOOT your PC
Installin USB & HBOOT drivers
On the phone:
- make sure USB debugging is on. – ensure device shows ok
-
Make sure PC connect mode is set to charge only
plug in your phone to the PC.
turn off your phone
boot into bootloader (hold vol-down while pressing the power button to turn on the device)
select HBOOT USB. you should hear your PC make the USB connected sound. When it starts to look for drivers, point it to that extracted zip folder. It will install the driver.
Once installed it will look like this:
next, boot into the bootloader again, but this time, go to Recovery (Vol Up to scroll, power to select). The same thing will happen on your PC. install the driver in the same way, or it may auto-install like this:
And show
next, boot your phone normally. When windows asks for drivers, do the same thing again.
Once you’ve installed the driver for these 3 different USB modes, you’re good.
At this point (if you haven’t already done so) switch USB mode to mass storage and copy the ROM .zip file over to the SD card. Switch back to charge only mode. If you don’t do this now you can still do it later thru recovery but just do it now, it’s that bit easier.
Install “Titanium Backup * root” (free) on phone – it won’t work yet, but don’t panic.
Reboot PC after above driver installations
Run unrevoked
Tried disabling AV on PC – same error
Tried plugging in phone afterwards – same error
Tried removing a few apps so the low disk space indicator disappears (uninstalled spotify, sleep as droid, sleep unlock, 4sq, etc)
Working better now… so lesson is you need approx 25mb free space
Waiting for bootloader – done
Rebooting again – boots into nromal OS
Waiting for system to settle..
Rebooting
Boots into HBOOT
Reboots
“I’m making a note here: HUGE SUCCESS”
Reboots into recovery
Success message, 10 second reboot
Reboots
Done!
Run Titanium Backup – confirm superuser rights
Problems – download busybox
TiBackup v 3.7.7.1 – root access OK
Menu -> Batch -> Backup all user apps + system data
Choose option to kill active apps.
Run Batch started 23:24:40 finished 2334. about 10 minutes.
Turn off phone
Turn on phone into HBOOT
Select recovery
Booted into CWM recovery
Choose option to perform backup
Started backup 2338 finished 2345
Once the backup completes, run wipe data / factory reset – instant
Once that is complete, Install zip from SD – browse to Redux zip (should be near the bottom of the list)
Wait.
You’re done!
Reboot and enjoy your phone!