after flashing radio, it was asking for a SIM

[emg75189]

ok im really new to this flashing stuff. anyways, i rooted my phone using unrevoked. i download rom manager but none of the roms would download. so i dowloaded Cyanogen Mod 6 and installed with USB. at first my phone would just restart, so i looked online and thought i needed to download and flash a "radio". when it started up again it was asking me to install a SIM. i freaked out and re flashed just the CM6 rom. everything works fine now and the phone it running smooth.

so my question is if i ever go back to my stock rom, will my 4G work again?

also will CM6 ever use the 4G? thats the only draw back.