Please, need help with 3G

hi fellow Gem owners!!  i just recently got mine and i cant seem to get my 3G network working.  i had a htc desire before and 3G works fine on it, but when i switched the sim card over to Galaxy i only get 2G signal.  there is no option for me to turn on the cellular data on. my mobile network settings only have data roaming, access point names, network mode, and network operators.  i got my phone from taiwan and i have hong kong cellular plan, does that matter?  thanks guys.

Firmware version:
2.1-update1
Baseband version:
I9000ZSJG4

Sounds like your new phone's 3G band plan is different in your country.

First, are the 3G band plans the same in both areas (Taiwan and Hong Kong)? If they don't match, then you will be locked to 2G. Have a look here: http://en.wikipedia.org/wiki/UMTS_frequency_bands

Next, is the phone from Taiwan or did it come from another area, like the USA? (i.e. was the phone for the Taiwan market or another one).

Who is your provider? Where are you located (Hong Kong?)