This post is less of a “how to” and more of a record of what I did. It could be useful to people who are intending to root their phone, but I strongly recommend reading the official updated guides.
I rooted my phone using the very helpful instructions at CyanogenMod, specifically for the HTC Desire please note my HTC Desire is the GSM version. I also used this forum post, which was very helpful in telling me how to use the Data2SD scripts. Data2SD allows you to use the SD card as “internal storage” so you can have a full 2Gb for apps, rather than using the phone’s physical internal storage which is far smaller.