Of course you know, that you get much more machine for the money if you buy a regular PC instead of a laptop. $3K buys you a REALLY nice workstation, and just a decent laptop.
In my opinion RAM should be your first priority. You want enough so that everything (Windows, Photoshop, your image files) fits in RAM, and windows does not have to page to disk. There really is no reason not to do full 64bit these days. You will find that laptops generally max out at 4GB of RAM (where as workstations can hold much more). I would max out the RAM with 4GB. (Dell is pretty proud of their RAM. What you might do is get the minimum amount offered in the laptop model you are looking at, and then go to NewEgg and buy 4GB at a nice savings.)
The next priority is to make sure you have as fast a disk as possible, and that is generally 7200RPM SATA in a laptop. Because laptops are designed for portability (and thus optimized for battery life), you won't find fast disks because they use alot of juice. High end disks on laptops are just standard drives on regular workstations. Disks are orders of magnitude slower than your CPU. When your CPU has to read from disk, this is a VERY slow (relatively) request than reading from memory. It does you no good to have the fastest CPU that can't run at full speed because it spends 30% of it's time waiting for IO requests to disk to complete.
Last, you should focus on CPU. If you have a scenario where everything fits in RAM, and there is no paging to disk, then CPU will be your biggest bottle neck. Get enough to make you feel good, but don't sacrifice RAM or disk speed to get a faster CPU.
Photoshop is a 2D application, and thus does not require a strong video card. If you don't plan on gaming, then the standard video card should be fine.
I myself am not a fan of the glossy screens. With dark backgrounds, there is alot of glare and reflection going on and it's very annoying to look at. I like matte screens.
