Pregunta a Hero Owners o Amigos :D

1) Goto dialer and dial *#*#4636#*#* (DO NOT press send)
wait a second and you will get the test menu.
2) In the test menu choose 'Phone Information'
3) scroll down and choose on the first drop down - GSM auto (PRL) (for high speed data)
or GSM only (You may get 3g if not use GSM auto (PRL))
Don't know what PRL means, but GSM auto (PRL) allows High speed data HSDPA
(it was previously on GSM/CDMA auto(PRL) I think.)
4) Back all the way out.
5) You might want to reboot, but I found the settings worked straight away.
Edit 3 - I don't take any responsibility for step 6 -
6) Try other settings on the dropdown if you are brave as I don't know
the consequencies of using settings like "EvDo only" and "unknown" as
they may be better depending on the way your provider provides information.
Edit 4 - can't seem to select the other settings like EvDo and unkown anyway.

Edit 3 - TBH - GSM auto (PRL) is working for me with HSDPA and I will try
(PRL) instead of GSM auto (PRL) <- edit - previously it mistakenly said GSM only
the CDMA and WCDMA settings later to see what other effects there are.