Upgrading Memory in New Vaio Laptop

[Wigwam]

FZ21z comes with the default 2x1gb PC5300 RAM
I want to upgrade to 4gb to make Vista home premium more responsive

Options:
Crucial Site Gives:
Crucial: 4gb PC5300 [667mhz CL5] = £61
Crucial: 4gb PC6400 [800mhz CL6] = £87

I have also found elsewhere:
OCZ: 4gb PC6400 [800mhz CL5] = £58

NOw I now that the PM965 chipset only supports upto 667MHz speed [PC5300] so should I:
-get the Crucial PC5300 as it is the most stable and compatible
-Get the OCZ PC6400 as it is slightly cheaper, better quality [as it is higher speed rated] and OCZ are a reputable SODIMM Maker?

Input is welcomed

 

[BassBomb]

Some motherboards cannot even read the higher speed RAM unless it automatically downclocks

Not sure how to find out, but most likely it will. In that case I would buy the OCZ

Otherwise I would buy Crucial to maximize compatibility

 

[Wigwam]

the Crucial configurator also lists the PC6400 Ram so I assume it does.