I have an external hard drive that will be used for backup. I am not used to the vista management and have a question. In the little box on the left it says Disk 5 Basic Online.
If I right click on it it brings up the box that says convert to dynamic disk and below that convert to GPT disk or MBR disk. On the other box to the right (the long one) if I right click it says New Simple Volume. Anyone care to tell me which to choose? Thanks.

It is basically giving you a choice between an Master Boot Record partitioning format, which is the current standard and bootable and recognizable from a standard BIOS driven Motherboard...

OR you can partition it in the newfangled GUID Partition Table partitioning format which is supposedly newer and better. It was started by Intel for their Itanium processor wich uses whats called an Extensible Firmware Interface, or EFI as opposed to a BIOS.

Since this is an external drive, and a backup drive, and you aren't running a server, and you probably aren't a glutton for punishment when it comes to being the first to try something new, then the MBR is the one you want.

I believe you can plug an MBR drive into an EFI architecture and it should still function, but if you plug a GPT drive into a BIOS architecture it may not support GPT, and depending on how badly it doesn't support it, your data might be inaccessible or worse written over. I haven't dealt that much with this, so if someone knows more, by all means post.

As for your situation, I would recommend just plain old MBR.