Question about flashing a ROM

Does anyone know if my phone is sim/cid unlocked, can I use the RUU to flash a ROM to my phone? It’s also called a HTC Wizard. Been on the XDA website, and know the general method to flash a ROM, but have never done it, and the Rom Update Utility seems so much easier.
Answer #1
If it’s factory unlocked then any firmware you flash shouldn’t affect that.
Answer #2
It is factory unlocked. Bought it off the web, and it had winmob 6 on it. I was gonna give it to a friend, and I reset it to factory settings, thinking that would just erase all the data, instead it reverted back to winmob 5. But can I use the RUU, or do I need all that lokiwiz, and button rom stuff?