Hello, ooh. PVC. Not a nice material, really and fairly short lived. In wood some areas may need decorating more - i.e the side where weather hits the most - but a good decorator should provide a good job and allow a wooden window to last ten years without painting. Wooden windows will last many, many times, more than that. I used http://www.joineryworkshop.com for my windows, a nice plug for an expert company. ;)
I don't know any companies but would definitely say go for wooden, it looks better and actually lasts longer and they do need repainting but not often. It does make a difference and if you ever think of selling it will help with that.