There's also a great product called Soilax that will clean the walls up. It says no need to rinse, but rinsing is advised. It's also found at paint stores and even some grocery stores in the cleaning isle. Here's a link to show:
http://www.jensco.com/thekitchendraw...eaner6150.html
If it's been a long time since these walls have been painted, then I suggest you prime them first, this'll ensure a better coverage with less latex. A good primer are the Zinsser products sold at Home Depot. As for a latex, use the best quality paint you can afford. You really do get what you pay for with paints.