Corporations cannot commit treason, nor be outlawed, nor excommunicated, for they have no souls - Sir Edward Coke
As always, the names are rather cryptic, but W1600UX2G7 is name for PC3-12800 kit consisting out of two paired 1GB DIMMs. This kit comes with CAS7, 7-7-18 latencies, while W1600UX2G9 has higher CAS9, 9-9-21 latency - but both work at same voltage, 1.8V. These kits are tested and paired with Asus P5K3 motherboard, somewhat a default choice for DDR3 motherboard testing out there.
Third one is very schweet one, W1333UB2G8 - a dual-sided, dual rank DIMM module rated at DDR3-10660. This stick of memory is built with highest density DDR3 chips (128M x8) out there, and we're not sure why the company decided not to launch W1333UB4G8 (2x2GB kit as well). It has to do something with pricing, we presume. This kit has been tested with number of P35 motherboards to ensure maximum compatibility with current motherboards.
When it comes to pricing, W1600UX2G7 will cost around 650 US Dollars, W1600UX2G9 will be priced 50 dollars less, while single 2GB DDR3-1333 module retails for 417 USD, which means the 4GB kit would surpass the launch price of 8800Ultra. ยต