I guess "Canyon" is "Cyanogen" (autocorrect striking again?). Does it actually have the google apps (e.g. Market) on it? They don't come with cyanogen by default, though almost everyone adds them.
You can certainly upgrade or replace the ROM. It doesn't require any software on the PC - you can do it all from the phone, using the "recovery" program. Unless it was rooted a very long time ago it will have a custom recovery, most likely "ClockWorkMod" or "Amon Ra", which will let you install a new ROM fairly easily from a zip file on the phone's SD card and perform other useful operations. There will probably be an app called "ROM Manager" on the phone, but do not be tempted to use that - it doesn't play well with the way most desires are rooted, and has often messed the phone up.
What I'd recommend is going over to the "all things root" subforum and reading the guides and faqs, which are linked in a sticky thread called "all about rooting". Your phone is already rooted, but start with the rooting FAQ anyway, as that will tell you about some of the things you can do when rooted, including how to flash a new ROM. It will also tell you how to get into recovery in order to do this. Read it a few times if needed, until it becomes clear. If anything isn't clear, ask in the forum before you try changing things - most mistakes are fixable, but we prefer people avoid getting into trouble in the first place.
You'll get a better response to this thread in the root subforum as well, so I'll ask a moderator to move it.
