WUXGA & nVidia Quadro

I have two Latitude D830 computers that I would like to consolidate in to one better unit.

#1 Processor: T7300

Bios: A17 RAM: 6GB

Display: WUXGA (very dim)

Graphics: Intel Chipset (shared memory)

#2 Processor: T9400

Bios: A16 RAM: 2GB (slot 2 (bottom) broken)

Display: WUXGA (full brightness)

Graphics: nVidia Quadro NVS (intermittent problems in high heat)

Options:

A: swap displays and make the #1 the best possible  

. . . can this be done?

B: Move 4GB module from #1 to #2 and make that the limit

. . . . Faster computer/graphics, reduced memory

C: Buy replacement motherboard to #2

. . . . Best of both worlds ... but extra cost

I have a #3 D830 which is like #2 (6GB) so keeping #2 will leave me NVidia allowing swapping HD's, but at reduced RAM or added cost.

Advice please

PS: If replacing the motherboard, do they all accommodate T9400 processors at rated speed?