When it comes to battery backup and portability people select netbook over laptop ,now with the arrival of atom dual core and AMD neo dual core processors netbooks can perform somewhat equal to an entry-level laptop .Here am sharing top 3 dual core budget netbooks currently available in the market .

Sony VAIO YB Series VPCYB35AN

Sony VAIO YB Series VPCYB35AN netbook comes with 11.6 Inch display with LED backlight ,AMD dual core E-450 1.65 GHz processor and 2GB of DDR3 ram.
performance wise device is pretty fast due to its dual core processor and DDR3 memory module,and we loved the sleek design and the funky colours in which its available .Only downside we found in this netbook is its battery backup ,can only provide 3 hours of battery backup with its 3 cell battery. Sony VAIO YB Series VPCYB35AN is available in market for $450 (rs.22800).
Acer Aspire One 722

Acer Aspire One 722 Netbook looks very plasticky ,and built quality is not that much impressive ,The netbooks comes with AMD C50 1.0 Ghz Dual Core processor 11.6 Inch 1366 x 768 Pixel Resolution LCD display and a great keyboard (keys are arranged very nicely) .
One of the notable feature we found in this netbook is 256 MB Dedicated ATI Radeon HD 6250 Graphics Processor there is not doubt that this device can handle Full HD videos smoothly and the 6 cell battery can provide up to 4.5 hours of battery backup ,Acer Aspire One 722 is available in the market for $380 (Rs.19000).
HP Mini 110 Series 110-3736TU

If you are looking for a netbook with premium looks and sleek design then you can consider HP Mini 110 Series netbook,It comes Atom Dual Core N570 1.66 GHz processor ,10.1 Inch 1024 x 600 Pixel Resolution LED display and 2 GB of DDR3 ram,
6 cell battery gives you decent battery backup nearly 4 Hours.HP Mini 110 is available in market for $380 (Rs.19000)