If you have a Lion installer on a USB thumbdrive, you can use it to upgrade your Mac from Snow Leopard to Lion, but if you have an older OS you can’t upgrade. You need to fist upgrade to Snow Leopard OR erase everything and do a completely fresh install of Lion. Here’s how.
Here are three different ways to put Lion on a USB thumb drive.
Installing Lion across multiple computers.
It took me a while to get my canon scanner working under Lion. The trick is that there are two programs that you need to install – the scanner program and the driver.