8.04 was supported from April 2008 until April 2011. The latest LTS is 10.04, which will be supported until April 2013 and the next LTS will be released in April 2012, supported until April 2015. Since 8.04 is no longer supported, you can't rely on software to be made available for it. But I see little or no reason why 10.04, and later 12.04, shouldn't support your computer.
There will be no official Ubuntu One support for 8.04, but there is nothing to prevent others from providing these packages. But since you also won't receive any security updates, using 8.04 is strongly discouraged.