A good link to a guide how to flash / use unrevoked is in thread of "wildpuzzle rom 2.1" in it's 1st post. Would be nice if u described what exactly youre problem is...
(refering: habs nochmal nach update vom hersteller mit Unrevoked probiert, irgendwie funzts nicht mehr richtig)
U told "unrevoked doesn't work anymore" where u get stuck? What does unrevoked tell u?
As u already have superuser app - it seems youre device is already rooted?!? As it gets installed by using unrevoked.
If u got stuck in unrevoked and restarted 2 early it could be u have to rerun unrevoked a 2nd time to get it fully rooted. But it seems u already have root now. so why to flash a rom now as u didn't want to as u described earlier...
u can enter recovery as described above
(turn phone off, hold volumedown + turn on phone while holding, wait some seconds, then u can select recovery by pressing vol+/vol- and enter it by pressing the power button)
Then u can do nandroid backup + flash new rom - don't foget to wipe old data before.
But as u described it's NOT what u want - as all u want is rooting (having superuser rights) and NOT a new ROM.
Rooting is independent from flashing a ROM. As well as the HTC GUI is independent from rooting.
So rooting WON'T change the ROM nor HTC GUI.
Anyway - if u still want to flash a new ROM and u don't wanna loose HTC gui - syncing with appbrain wont help u as HTC GUI is not out on the market. So it can't be reinstalled by appbrain after flashing a rom without them.
If u want htc gui / apps u have to take a rom with them preinstalled (u can't take crayogen atm as it comes without htc apps).
For a list of roms with/without see:
Get more inforamtion in the rom thread - and read before u flash - as each rom has different "problems".
If u don't wanna read whole thread - at least read the first 5 posts + the last 2 sites of a rom so u can get a little view of the problems/possibilities people face.
So all in all: U had an "old os" - rooted it - and t-mobile did an upgrade - after it root was gone?
1. get UNREVOKED running - if u face problems (and u did as it seems) - tell which? not just " irgendwie funzts nicht mehr richtig" next time
2. u can decide to do a nandroid backup after (i would recommend it - as a rooted rom has the "capability" to brick)
3. u can decide to flash a new ROM but there is no need if u just want to have root rights.