ok... I'm not sure if your budget is 40,000 or 400.00 dollars. If its 40k, go for the most expensive mac. If its 400, go for a windows laptop in newegg with a i5 processor for 399.
It depends on the money you are willing or are able to spend on this laptop as well as your requirements If you are not limited in resources I wold recommend to get Macbook Pro or Sony Vaio SB series laptops If your resources are limited I would be looking for Macbook Air or some PC alternative or something even more cheaper
I use Acer Extensa 5625ZG and I'm very happy with it. I think it's well worth it's price. Here are some more and newer models of the Extensa series by Acer (this is NOT an affiliate link): http://www.amazon.com/gp/search/?rh=n:565108,k:acer+extensa&keywords=acer+extensa
I have Asus, great video card. But if you can afford a Mac. That would be the best, but if you're not a Mac guy like me. I go with Asus, Toshiba I would avoid HP.
Based on your Budget, I can say Dell N5010 is the best option to buy. Recently I bought the Dell Laptop model N5010. Excellent design, great performance. I bought it for 37000(INR). Here is the Configuration. * Core i3 processor * 320GB - Hard Disk * 3 GB RAM * 15.6' Screen * 1 GB Graphics Card Bluetooth, Wi-Fi features support. A worthy buy for a long time use. All the Best.
I used for 3 years Lenovo. I didn't have any problems. Now. I'm using mac book pro, it's very fast and very pleasant for eyes, so if you need your laptop for IM, you can't make mistake with Apple.