Thinkpads are just owned by lenovo. Designing, manufacturing and all is still handled by same IBM team, I think even service department is separate.
Hp laptops are also good in terms of quality, yea previous models use to heat like hell but new one comes with cool sense technology makes it normal laptop (even better than my friends XPS 15).
ASS and all is 10/10 by hp for me they just replace with new part if I say on customer care, they replaced my DVD burner that i broke accidently.
But ASAIK new 2012 models by hp are overpriced and having worse conf than 2011 model.
For you Dell Inspiron 15R SE would be the best choice. It is a VFM right now, you can wait other models to compete with this in a month or so like hp may launch new dv6 model with GT 650M like they do in US.
Last year in july they launch a better 2GB graphic model 6121tx replacing 6017tx.