shouldn't make too much battery difference -- what DOES use a lot of battery is full screen display such as EXCEL / Powerpoint, and lots of HDD accesses.
On a Netbook the CPU won't use a lot of power even when running at 100%.
Incidentally the BEST way of improving performance on a netbook is to up the RAM to 4GB (4GB single modules are cheaply available now -- DDR3 type is probably what is in your netbook) and to use an SSD.
Using an SSD instead of the internal HDD will make a dramatic improvement in performance on a netbook. SSD's are becoming actually affordable now --even for impecunious students !!.
Upping the RAM also has a beneficial side effect -- since more data can be stored in RAM you will have less DISK access -- hence less power drain. RAM itself isn't a huge consumer of battery power.
Switch also to Power saving mode in Windows in the Power plan options (Control Panel) -- chose the option "On Batteries".
I upgraded my Acer Aspire 1 to 4 GB RAM and swapped the HDD for an SSD -- performance is perfectly acceptable - especially for on the Road -. You can also connect it to an external monitor when you are near a power supply if you prefer working with larger screens - but since most of the younger generation are perfectly happy staring into tiny mobile phone screens all day long a netbook should be just fine.