OT - USB Booting

[MJang]

Folks, 

I'm trying to see how to boot a USB key drive from an older PC. Have
tried upgrading the BIOS, and that doesn't add USB boot abilities. 

Just wondering if there's something similar to the Smart Boot Manager
http://btmgr.webframe.org/ It's great as it gets around this PC's BIOS
problems with CD booting. But it isn't yet updated with USB boot
features, say from a key drive.

If someone can suggest a better list for this question, I'm all ears.

Thanks,
Mike