Booting from USB key

I have a 4Gb USB key with Ubuntu 9.04 installed on it, but I cannot boot from the Key, I have tried all 4 USB settings in the BIOS, I have tried using the F12 key to select a bootloader, but nothing works.

I have a EP45-DS3 Motherboard and dual boot Vista Ultimate (32bit) and Windows 7 (64bit). Do i have to change anything else in the BIOS besides selecting USB as the 1st boot option.

cheers

One BIOS setting is important:
on the "Integrated Peripherals" page, "Legacy USB storage detect" needs to be "Enabled" (in newer BIOS, this is sometimes called "USB Storage Function" ) only when you want to boot from USB, or need access to USB for some BIOS-related function, like the <F11> saving CMOS parameters to a key, or flashing from a key. What it does is load USB drivers with the BIOS, so you can access a key before the OS' drivers are in place - but, at all other times, you want it "Disabled" - it's a major cause of the dreaded 'Gigabyte reboot looping'...

Well i set the "Legacy USB" to enabled, but still cannot boot from the USB key . are their any 3rd party bootloaders that would allow me to boot from the key.

cheers

Found this:
Can I use USB 2.0 or IEEE 1394 (FireWire®) Devices with BootIt NG?
Yes; support for USB 2.0 high-speed hard drives, pen drives, CD drives, and DVD drives was added in BootIt NG version 1.50, and is available in the Partition Work dialog.

Likewise, support for IEEE 1394a and 1394b (e.g. "FireWire®" ) high-speed hard drives, pen drives, CD drives, and DVD drives was added in BootIt NG version 1.60.

Please note that to use a USB 2.0 or IEEE 1394 device, you must first enable the applicable option in BootIt NG's settings. To enable USB 2.0 support, select the "USB 2.0 Support" option, and to enable IEEE 1394 support, select the "IEEE1394 Support" option. With those settings enabled, the USB 2.0 and/or IEEE 1394 drives will be enumerated after the BIOS drives. USB and/or IEEE 1394 CD/DVD drives will be located under the CD radio button.

BootIt is available here:
http://www.terabyteunlimited.com/b [...] ration.htm