You don't need to install it to try it out, just run it from the CD.
If you do decide to install, take care if you've already created a partition as it won't automatically install itself onto that partition & will try to create its own so you could end up with 3 patitions, 2 of them small.
My only problem with (K)Ubuntu is it's made by a crowd of hippys who refuse to include anything proprietary which means no multimedia codecs by default.
A much better option IMO is LinuxMint which started as a deviation from Ubuntu but with everything working straight out of the box, Ubuntu on steroids.
I only use Mint on my home PCs, wouldn't go back to Windows, not because of any Microsoft hating madness, it's just better IMO. Windows apps aren't a problem either I have several of them, that don't have a Linux version, running quite happily.
I use Vista, XP & Mint on a daily basis & MInt wins everytime.