Late 2008 Apple Aluminium MacBook complete reinstall I have a pretty  old Aluminum Macbook (late 2008). I pretty much have the original MacOS installation, continuously upgraded to Mac OS Yosemite. Nowadays, it is kind of hard to get by with 250 GB of HD, so I  thought about upgrading to a bigger HDD.

I kind of have the feeling that a clean reinstall of MacOS after 6 years of running it would be a good idea, at the same time I do not know where the original installation CD is left. Is there a way to install Yosemite directly??
If you have a spare 8GB (or bigger) USB drive (or an external hard drive, or even an unused partition on your internal hard drive), you can download the Yosemite installer from the App Store and use it to create a bootable Yosemite installer. Here are Apple's detailed instructions for doing so.