CSV files are automatically associated with Excel but when I open them, all the rows are basically in the first column, like this:

Turns out it was a regional setting issue;

Go into your control panel –> Regional Settings –> Advanced Settings and change your list separator to a comma.

Mine was set to semi-colon for South Africa after I changed to Windows 8. After I changed it to a comma, all my CSV's open correctly with Excel 2013.

Hope this helps.

Additional comment:
I used the same steps as Lèse majesté, but I also changed the Decimal symbol from a comma (,) to a fullstop (.) and it fixed my problem.

This is because, by Default, Windows 8 uses a comma as a Decimal symbol and Excel gets confused when it has to use both the characters as separator and Decimal symbol.