New Acer laptop batteries struggle with a max 4 hours battery life

The Acer Aspire 721 laptop batteries costs around ?350, it's very thin, has great HD content and Flash playback facilities and is very affordable at the aforementioned price. However, its battery life is fairly weak, only last 4 hours in optimum conditions. This is mostly due to it's processor, an AMD CPU as opposed to the usual Intel Atom processors that we find in netbooks these days. AGAIN, like the 721, the battery can barely last 4 hours. This day and age, it's all about the battery life with most manufacturers going for 6+ cell batteries that'll keep going all afternoon.