Use EZ-Flash and flash by USB stick, see your user manual. You can download your bios at the ASUS website, see link. Check and double check to make sure you are downloading the right bios file for your board. Download bios M3A78-T BIOS 1104
There is the Phenom X2 550 BE, excellent dual core for just $100, then the Phenom X3 720 BE, my favorite since its three cores, for just $140. Then there is the Phenom X4 940 BE, at just $190, and a step up further than that is the Phenom 955 BE at $250. All the best choice for the money.