I'm a little late to the party here, but I recently acquired a Desire. Within an hour of having it I'd rooted it and flashed a custom ROM. Its a pretty simple process and from what I can see you really can't fail, if it all goes wrong then just flash it again. Having said that I've now tried most of the custom ROM's available and if I'm being honest they are a little bit dull, some add a few nice features, but for the most part they are much the same. Also the boot time is now horrendously slow.