[Q] New desire z user here.

probably isnt locked, but those are two separate things. you can have an unrooted and unlocked phone, a rooted and locked phone... etc

The term "unlock" is confusing, as it can mean several different things.

Since a SIM works from a carrier besides where it was purchased from, it appears the phone is not SIM-locked. But that has nothing to do with S-Off and root, which is what you need for flashing ROMs, kernels, or any mods/apps that require root.

If I recall correctly, some of the European Z's are sold unbranded, and possibly not SIM-locked. But as far as I know, you will never get a phone from your carrier that is S-Off and rooted. Follow the Wiki method to get S-Off and root. And if you do so, it doesn't matter whether its SIM-locked or not, as it will be SIM-unlocked after the S-Off and root process (gfree does S-Off, root, Super CID, and SIM unlock).

Other new desire Z user, and i change a cyanogenmod 7.1 (for now) ...

In Romania, most phones are sold unlocked. That's kind of a general rule, so 90% chance your phone is unlocked. Try another SIM - Cosmote maybe - and see if it works

Yep, battery life on the stock battery just sucks. Also, I'd advise against sense 3.x because it's too bloated and thus slow for our device. If you want sense then wait for the Sense 4 ROM's to become fully functional. They are a lot faster and lighter. Otherwise, there's plenty of ROM's to choose from, so pick your poison

Sent from my DZ.

Gfree is recommended. Most on here will agree that it is the safest way to S-Off and root.

Virtuous V2 is a good Sense ROM. Its Sense 2, but is stable and fast. Sense 3 ROMs have some cool features and eye candy, but is designed for more RAM than our phone has, so it lags badly. ILWT CM7 is a cool AOSP ROM. And MIUI is good if you are looking for something different from Sense and AOSP (simple and elegant interface).

Battery life is largely dependent on how you use your phone, network reception, and other factors. But I can get close to 2 days with light usage, 3G at work, WiFi at home, Bluetooth on. Widgets don't seem to make a difference in battery life to me. I have 3 pages full of widgets. On the other hand, I've seen my phone drain to almost zero within 8 hours or so, when hiking in the woods in poor reception areas, without using the phone at all.