ok this is what I want you to do, Go back to the tmobile store and tell them you hate this phone.
Then wait till july 16th to get the samsung galaxy S.
Or you could go to google.com/nexusone and buy the nexus 1.
This phone has reached its max and I would lie to you if I told you it was a good phone.
If you bought this phone off of ebay or someone else,
then.......
Hello! Welcome to forums! Please look in our All Things Rooted to learn more about Roms and flashing.
ODIN is our flashing program.
Our roms are currently
1.5 stock (which is what you have with a brand new behold II)
1.6 oem update rom (which is what samsung recently gave us, our LAST update from them)
1.6 oem update tweaked rom (which is what samsung gave us, but without all the extra programs)
1.6 no twiz behold II [take5 is the newest one] (which is a user made rom that integrates 1.6 without the touchwiz interface)
1.6 galaxy rom [r12??] (This is the fastest, and best on battery life, HOWEVER it has not vibrate and it does not let you use your 5 mb camera)
Have fun
ps, DO NOT FLASH THE 2.1 ROM, its far from ready. Actually it will never happen unless we get source for the drivers, (which we never will)