A live distro for online banking? I would not suggest such.
Why? A live distro do not leave temp files, cache, etc. on a hard disk drive to recover sensitive data after use, less chance to get the original media, specially a CD to get infected, etc. Maybe I'm wrong, but for me it seems to be secure, at least as secure as an installed system.
In complete agreement with your comment that LiveCD should be just perfect for online banking, I just want to add that in fact it should be safer than installed system to use for this purpose. With installed system you do not have the pristine state each time you boot and in fact you never knowif any viruses, trojans, rootkits or keyloggers had a chance to implant themselves. Prticularly with Windows, where being connected to the Internet alone exposes you to these threats constantly. Antivirus tools are only effective to some extent, so you are never sure 100%. Rootkits hide beneath the OS and are not visible to trojan and virus detection software.
With LiveCD pristine state you do not have this uncertainty, as the exposure is reduced to only the current session and if you are not browsing dangerous sites before online banking, the online banking should be as safe as can be.
Fact is that password on sudo would further enhance security level and is therefore quite valuable. This is what the originator of this thread is asking for...