go for a 17" one, as from my personal experience, ts very difficult working on small screen, while modeling and even some dialogue boxes fail to show properly vertically, 17" one has a P8700 cpu, if you are interested in i7 only ,call up the dell and chat with any sales executive regarding pricing and customization,
in UK it would more costly compared to here, if possible get from US, for this budget you would get 18.4" models,
I dont know whether 1.5gb portable hdds are available, however 500gb WD would be little less than 5k.
you can look this from HP -
http://www.priceindia.in/laptop/hp-p...-2213tx-price/, however dont rely on the pricing of that site.