Saroj,
Everything I say is from experience from owning the computers in question.
You don't want a Dell laptop. You won't get nearly the computer you need for your money. And they die quicker than others. A tech once told me that if a laptop lasts more than two years, it's on borrowed time. I have one (not a Dell) that is going on six, but it's beginning to sputter it's last breath, LOL.
My first choice for a PC would be the Sony Vaio. They are made as close to a mac laptop (quality wise and design wise) as possible, just extremely well made in every way....HOWEVER...
I really would say if you don't mind switching OS, go with a mac. You can't go wrong, you don't need to purchase virus protection, and if you are lucky enough to have an Apple store within an hour's radius, that's all you will need when it comes to service. They are the best at customer service I have ever dealt with.
The MacBook Pros are pretty pricey, but when you see the design, you'll see why. They just don't break. They are made with one piece aluminum construction.
IF you want a reasonable alternative to a Macbook Pro, you could try a Mac Mini. It isn't a laptop, but the cool part is you buy the monitor that you like (there is no laptop monitor good enough to edit professional photos on, so that's what I do), and get a wireless keyboard and mouse from Apple, and you have a very portable computer that is compact and is really fast for about half what you would spend on a MacBook Pro. You could get a giant monitor, but not the mess and wires that a desktop pc would add. I use my Mac Mini to hook up to my tv to watch Netflix movies on, as well as edit photos, etc. It's so versatile.