Install a new blog or make a new category?

Hi guys

I need to run multiple blogs, and i’m trying to decide which is the best way to go about doing it.

I can install a new version of wordpress each time i want a new blog fair enough. However, I could have just one blog and each time I want a new blog, create a new category.

Can anyone provide me with the pros and cons of both options?

Just having different categories, means just 1 database, and 1 install, but I don’t know if i’m going to lose out on functionality at all….

Thanks for any responses

Regards