Developer Laptop

After living with my junk Lenovo for last three years (battery gone bad after 1 year, HDD is slow as hell), I am looking forward to buying a new laptop for development (personal), basic email/browsing etc. No games, no high end photo/video editing.

What would you guys recommend? Are there any good build laptops which will survive my three year upgrade cycle?

I have a Lenovo T410 from work which I like but hate that it needed a battery replacement in first month and identical machine for co-worker needed a motherboard replacement (again in first month).

I am leaning towards getting 13’’ MBA and installing Win7 on it, considering that I don’t need and want to spend on MBP. Lack of 4GB in basic model is definitely drawing my attention.