T400, T510, or T530? Need to keep one, sell the others.

So I've got quite the collection of ThinkPads, all of which are repaired/refurbished surplus machines from my local university and thus acquired cheaply. I'm clearing out a lot of my tech in preparation for a move, and I want to keep a single ThinkPad and sell off the rest. It'd be mainly a secondary/portable machine to my 2011 MacBook Pro 15", which stays tethered to my desk w/ a large display. Battery life would be nice, but not a hard requirement. I'd be using it mainly for document writing/note taking (grad student finishing my thesis), and possibly some light gaming (L4D2, TF2). I'll be running Windows 7 on it.
Important specs are as such for each model, everything else is modular/upgradeable. All have 4GB RAM, and I have a 256GB SSD that I can put in the winner.

T400: 2767-R2U, T9600(2.8GHz), 14.1in 1440x900 LCD, 256MB ATI Radeon HD3470 (switchable w/ intel 4500 graphics)

T510: 4349-WJ8, i5-520M(2.4GHz), 15.6in 1920x1080 LCD (upgraded) 512MB nVIDIA Quadro NVS 3100m (discrete, non-switchable)

T530: 2394-AK1, i5-3320M(3.3GHz), 15.6in 1920x1080 LCD, Intel HD 4000 Graphics ( integrated only), still has 1.5 years of warranty left

I'm deciding between the T400 and the T530 right now, but I wanted to mention the T510 in this discussion as well. Thoughts?

 

If these were mine, I'd keep the T400 since it's the most portable one of all, and has the least $$$ value of the three.

 

if you want to get most money out of the sales, sell the T510 and T530. If you want keep the machine as main laptop for use, then keep the T530.

 

I'd keep the T400 and sell the rest, you aren't going to get alot for that T400 even it being top spec (switchable ATI, T9xxx Core 2 Duo, WXGA+)

I've never been a fan of 15" ThinkPads, too big and bulky for me, unless you were talking about a 15" 4:3 UXGA Flexview, then the bulkiness would be forgiven.

 

Did some weight comparisons, and it feels like the T530 is *lighter* than the T400. I'm going to do some CPU/GPU benchmarks today, as I'm interested in seeing how the integrated HD 4000 chip compares to the Radeon HD 3400 in the T400.

Thanks for the advice so far, keep it coming. Still deciding...

 

and you yet you prefer the slim 17 inch Alienware and Sager.

 

Well I meant for work purposes, those sit on my desk for gaming. I used to have 11-13" laptops for portability/on the go (Latitude 13, X220t, X201, X200t, X61t, X60t, T410s, Alienware M11x).

3470 Mobility really is a low end card, slightly above a 9300M GS...which even Intel HD 3000 is faster if you have the appropriate RAM.