Laptop advice required

Sometime around March I'm going to be moving to India to start work with a charity in Gujarat and need to take a laptop with me to work on. Although it will primarily be a work laptop, I plan to use it for entertainment and a bit of light photo editing too. I do play games such as TF2, Dead Space, Call of Duty and others but as long as I can play games I'm not worried about being able to get the best graphics. The priority here is on work I suppose. So:

1_What is your budget?
Lets say up to £750 but I can be flexible here.

2_What is the size of the notebook that you are considering?
15", possibly bigger, probably not smaller.

3_What screen resolution do you want?
Unimportant

4_Do you need a portable or desktop replacement laptop?
Portable

5_How much battery life do you need?
I will be doing field work so as much as possible.

6_Do you want to play games with your laptop? If so then please list the games that you want to with the settings that you want for these games. (Low,Medium or High)?
Yes, as mentioned above. Low to Medium.

7_What other tasks do you want to do with your laptop?
Light photo editing, watching films and perhaps TV, listening to a lot of music.

8_How much storage (H.D.D Capacity) do you need?
All my music videos and pics take up 304GB, so more than that. Preferably at least 500GB.

9_If you are considering specific sites to buy from, please post the links to them.
Any reputable retailer is fine.

10_How long do you want to keep your laptop?
2-3 years.

11_What kind of Optical drive do you need? DVD ROM/Writer,Bluray ROM/Writer,Etc ?
CD/DVD writer.

12_Please tell us about the brands that you prefer to buy from them and the brands that you don't like and explain the reasons.
I used to own a Fujitsu-Seimens Amillo M3438G, and after trouble with the graphics card over heating and the piss poor job they did of fixing it I vowed never to buy from them again. A lot of my friends have Dell laptops and from what I've seen they all break as soon as they're out of warranty, and after a year or so of use are slow to the point of being unusable.

13_What country do you live in?
UK

14_Please tell us any additional information if needed.
I need this laptop to last in hot and dusty conditions and not to break on me as I imagine getting it fixed would be a nightmare.

Thanks in advance for your always wonderful advice .