The faq outlines the procedure, and the All Things Root Guide post also has a link to a list of ROMs at Xda. That all done, you can think about changing ROM. This is a "nandroid" backup, which lets you restore your ROM and all data if something goes wrong. Then before changing anything, boot into recovery (boot while pressing the volume down key, then select recovery from the menu) and take a backup from there. Contacts should be backed up to sd (import/export) or to Google.
#HTC SYNC MANAGER GOOGLE PLAY PRO#
The Pro version lets you do batch restores, and also backs up call logs and messages in a way that can be restored between ROMs (otherwise you want an extra app to back these up). An app like that backs up your data to sd, and you can then restore them to the new ROM. When you change ROMs you must perform a factory reset, which erases everything. If you have apps and data you wish to keep then I recommend Titanium Backup (esp the paid "Pro" version). The most important thing is taking backups before changing anything. That contains links to a number of useful threads, and I suggest reading " Rooting" first - you are rooted, but that includes a lot of other info, including the basics of ROM flashing. So the starting point is the sticky thread Desire All Things Root Guide in this forum. In principle changing ROM should be straightforward, but there are a few steps, a couple of things to watch for, and it's best to make sure you understand what's needed before trying to do it. So if you want to use that then you will need a Sense ROM. HTC Sync only works with ROMs based on HTC Sense software. Apologies, this is long, but I hope will help.