loader screen

hey guys, i need some help here with linux. im not very good with linux so hang with me. I have a few flash drives that I use to work on peoples computers, I have different bootable operating systems on each for different purposes and would like to put them all on 1 drive. Once all on one drive i would like to have a screen that allows me to pick which OS i want to load. Im not sure what this screen is called so searching google landed me no where.

A. How can I load multiple OS's on a single drive and

B. How can I choose between them?

thanks!

Create multiple partitions and install a boot loader. You can use something as simple as mbr (Linux utility) which on boot gives you the option to type numbers 1-4 to boot a given partition.

Isolinux can also be used to create bootable CDs with many different image files but is a bit more complicated to use.

Check out the ultimate boot cd and see how they have set it up. It is well documented.

Will this work on a usb flash drive?

I found a website with different boot loaders on it, I assume they all work the same way?

The Ultimate Boot CD is actually one of the OS's I want to include on this drive, Can I edit its boot loader to include the others of my choice?

Sort of, but you have to figure out if you are booting images or booting filesystems/partitions. It works differently. Read up on the differences between syslinux and isolinux.