Consumer Reports currently says Dell Inspiron 530 (Workhorse) for the money
check out the Dell website and you can build your own.
HPs are also good and reliable and you can probably build one from their website too.
Make sure you buy a LOT of space, pictures are hungry critters!
I would not recommend a laptop for a photography business at all.
Laptop screens, because of the tilt, especially in photoshop can produce distorted colours, eg you might look at the image and because of the angle, think the brightness level is correct. However when you go to print it, the image may appear way darker.
With a desktop and regular calibration of both printer and monitor, this is easier to avoid.
A pc with a high quality graphics card, about 4gb of ram, and something like a core 2 duo processor to keep up with photoshop. A great deal of space would also be necessary, but you could always buy an external harddrive if that’s an issue - they come fairly cheap these days.
This might not be what you are looking for, but when it comes to creative endeavors a MAC is the way to go, and yes you can get Photoshop (and any other Adobe product) for MACs.
With any laptop I would suggest that you purchase a desktop monitor so that you can plug it into your laptop while at home. This will solve any screen issues that the other guy was talking about. Really with the MAC laptops you shouldn’t have any issues, The colors are awesome. take a look at the Apple MacBook Pro .
And yes, there are plenty of USB SD card readers on the market. You plug it into the USB port on your laptop and put the SD card in on the other end and voila. Here’s an example
It sounds like your looking for a Windows laptop but consider an Apple. Great software, community, and no viruses.
If you want best i would get a apple mac book pro BEST for powerpoint. If looking for less money I would get a HP.