To get the number pad, you are pretty much limited to 17" laptops. The upside is they usually have really nice screens!
I have an older Dell XPS (M1730) that I have been extremely happy with. I have had 3 Dell laptops so far, and I would not hesitate to get another. However, don't spend less than $1500 on a Dell computer or it will be crap. Also, wait for rebates to come out, you can usually get at least 15% off Dell stuff if you watch for a few weeks.
If you are going to run those engineering tools, make sure you get at least 8 GB of RAM and a dedicated graphics card. The nVidia Quadro cards are great for professional applications, but don't game well. The GeForce line games great but only does OK on professional applications (this is what I usually get). Having 2 hard drives is nice too. I have a SSD and a regular drive, so I get the best of both worlds (performance for applications; and lots of storage for documents, music, movies, etc.).