Windows 7: Tablet battery life- is there a software solution?

I'm in the market for a new tablet just with the following wish list-
6 hour+ battery life
Windows 7

...and thats about it.

I've had a chinese tablet in the past with windows 7(probably not a legit copy) and after tweeking and optimizing it, it could run like the wind with everything I threw at it.

Only issue was the battery, would last 2.5 hours max between charges, totally impractical.

80% i was using it to read ebooks/daily newspapers in work and generally browsing the web while sitting with my feet up watching tv. The other 20% of the time I'd be streaming tv or radio, the odd video call and some fiddling with work stuff in office. For most of what I needed it for, Android couldve done the job but there has been a few times where only a full on Windows 7 system could save the day, for me its a must.

So has anybody here got a tablet running windows that could last me a solid 6 plus hours?

If not, is there a software solution to stop power being destroyed? Would give me options.