I have Windows Vista OS with 2 GB RAM in one slot and 1 GB in the other of only 2 slots. Both are Transcend DDR2 of 800 MHz with identical 5-5-5 latency. I would like to upgrade to 64 bit Windows 7 with 4 GB RAM. if I replace the 1 GB RAM in one of the slots with a 2 GB RAM of same brand and specs as the 2 GB RAM already in the other slot but of latency 4-4-4, will my desktop work and if so with what result? Thanks in advance for your advice. Vasudev