Buying a new computer, which is better: Mac or PC?

My dad is buying a new desktop computer for the house (for everyone to use) but we don't know what to buy. Right now we have a Dell computer which we really hate because it's really slow and has 0 virtual memory left. We bought it back in 2005 so we think it's time for a new one. So what's a better computer Mac or PC? We usually only use our computer for music (putting music in our iPods with iTunes), uploading camera pictures, and surfing the web. We don't use it for gaming. Also I would personally want microsoft office for school work. Are both computers good for that? And which specific desktop computer do you recommend (Example: Mac mini or HP touchsmart) and do you know when the newest version comes out? Sorry for the long details and thanks before hand to all your answers :)