I have decided to use the 32GB SSD cache drive for Windows 7 64bit. Although the main purpose of the machine will be for OS X 10.9, I decided to keep a Windows install handy for the Battery Reset utility and the Fan Cleaning utility (spins the fan at max speed alternating between forward and reverse). The hardware transformation is complete, and the OS X 10.9 install begins today.
Here is a rundown of the upgrades so far:
Intel 520 Series 180GB 7mm SSD
8GB DDR3L 1600 Crucial Ballistix
BIOS whitelist removal
AW-NB037H WiFi + Bluetooth combo card
TIP: You do not need to remove the Fan/heatsink assembly to swap out the keyboard on a U310. The HMM states that removing the fan/heatsink is required, and that is NOT TRUE. Also, the battery does not need to be completely removed, just partially lifted a little to give yourself room to push the keyboard out from the bottom.
R400 7439W1K- 8GB, Momentus XT 500GB, Intel 5300 WiFi
T410 2518X01- 8GB, Corsair Force GT 120GB
T410s 2901A3U- 8GB, Intel 6300 WiFi
T420s 4174PPU- 16GB, Intel 520-series 7mm 180GB & Crucial m4 mSATA 256GB, Intel 6300 WiFi
and a few classics in storage