if you have an old generation, you'll get nothing but crashes
lies.I have a 8GB 3rd gen (running iOS 4.2.1), which is a pretty much a 2nd gen with bluetooth, and it runs just fine. I have backgrounds enabled and some extra eye candy here and there.
If you used greenpoison to jailbreak it however, I wouldn't change the bootlogo, it sent my iPod into an endless loop and I had to restore and re-jailbreak it.