Most independent retailers offer no-OS option.
Try these well-established stores:
Many of the Sagers at discountlaptops and ASUSes at proportable have high contrast screens.
If your primary need is expanded data storage, then get a 3.5" desktop drive ($100 for 300GB) plus an enclosure; if your primary need is increased system performance, then find out your bottleneck.
Perceived sluggishness on a...
Backlighting on laptops are attenuated for power conservation, and are not in the same class as those on desktop LCDs. It is therefore not wise, both economically and practically, to use a high end panel in a mobile configuration.
Get a firewire external enclosure (be sure it has the Oxford chipset) that has a good built-in fan, and pop in an HDD of your choice. SATA is a waste of money for an external setup, so just go with the regular stuff.
I have a 3.5"...
You'll need a high performance processor and lots of ram; dedicated video will not be necessary for the programs listed.
If the Dell and Lenovo are priced similarly and only Dell has included warranty, then the choice is easily Dell.
You can contact Justin (firstname.lastname@example.org), who runs www.proportable.com
He's among the most knowledgeable people in ASUS hardware specs. If anyone knows the details you're looking for, it should be him.