Dual booting is just fun. Being able to show your friends that you can boot into two different ROMs is bragging rights enough. However, dual booting can also be useful. Perhaps one ROM for business, one for pleasure, for example. In any case, when a phone gets the ability to dual boot, it’s worth trying at least once.
For owners of the LG GT540 Optimus, you now have the ability to dual boot ROMs thanks to work by XDA Senior Member Sardonis. Using his method, one ROM is loaded from internal memory, while the other resides on an SD card.
As with most dual booting experiences, the method can be a little complicated. So if you’re thinking of giving this a shot, be sure you back up everything, and pay extra attention to the instructions. For the time being, the selection of bootable secondary ROMs is small, but you can still flash whichever ROM you want as the primary.
For anyone who’s looking to try out some dual booting love, you can find all the download links, the full tutorial, screenshots and a nifty, helpful video in the original thread._________