Look into Asus, they're the best laptop brand out there. Sony laptops are terrible as they have very cheap parts in them and the same can be said about Mac's. At least Asus are very well known for making top quality PC components (they make almost every component) and they have excellent customer service.
If you get a Laptop with Windows 7 make sure it's got at least 4GB of ram because Win7 runs slow with less than that amount of ram and make sure it's a 64bit version.
as for portability Echoes, look for the "SU" core Netbooks not notebooks. They have decent power, basic to fairly good graphics processing (depending on the chipset) and quite fast depending on other specs like Amount of ram, graphics memory (make sure graphics memory isn't shared with ram, it'll slow it down) but lacks dvd burner, hi end graphics, and other power consuming devices.
But Battery lasts anywhere between 15- 20+hrs. If you won't use power demanding programs this is a good choice.
Or just get a decent Asus, HP, MSi, Samsung Laptop with LED screen, power efficient models with 8 cell Battery. Should last a good 10+ hrs.
Good Laptop Brands: Asus, HP, MSi, Samsung and Toshiba (though it's not really good value- overpriced).
I work in IT in Australia and have been doing so for 5+ yrs. Hope it works for you both 