I'm thinking of purchasing the following:

2Gb (2X1GB) Corsair TwinX XMS2, DDR2 PC5400 (667), 240 Pin, Non-ECC Unbuffered, CAS 4-4-4-12 £55.80 (scan)

to be used in an ASRock Conroe 945g DVI board. The question is will this work with 2 x 512 Corsair VS DDR2 PC5400 (667), CAS 5-5-5-15? At what CAS latency?