Any Froyo compatible radio will work.
You check by looking in the "about phone" menu, software information. It's called "baseband". If the version is X._5.Y then you're fine. But unless you are still using 2.1, you are fine anyway.
Note that version information above assumes your phone is GSM - I don't know CDMA, but then there don't seem to be a lot of radios for CDMA available anyway.