So after getting very annoyed at my HTC Desire constantly running out of space due to all the unremovable apps on the phone memory I snapped last night and rooted the phone.
Firstly used unrevoked to root the HTC Desire.
While this got me root it left me with a locked boot loader. (S-ON repport by the bootloader.)
Then used revolutionary to get the boot loader unlocked.
Then installed SuperUser from the App Store to manage root use by other apps and then installed ROM Manger.
Finally used ROM Manager to install cyanogenmod.
After successfully booting into cyanogenmod the Android market was broken giving error message,
Error downloading “[App Name]”. There is insufficient space on the device.
Tried clearing all caches, and eventually found that reformatting the SD card and then running MarketFix sorted the problem.
Would like to acknowledge the assistance offer by Cyanogenmod wiki.