Its a long process but in short,Go to Settings>About Phone>Software Information and tell me what are the entries there.??
Another way to check it to Turn off your device,Pull out its battery for 5 secs,then put it back in,then press and hold power button along with volume down key at the same time,dont let it go until you see white bootloader screen,if you see RECOVERY option on the screen,your device is rooted.
BTW,If your EVO running on Android 2.3.4 then there are no further updates to install.