Laptop won't turn on with new RAM

[christopher fletez-brant]

I am using a vaio vgn-fs630w, which came stock with 2x(256mb 333mhz ddr) for
a total of 512mb RAM. I just bought 2x(512mb 333mhz ddr) so that I could
updrade the machine to 1gb RAM, and then to Windows 7 (it's for my
girlfriend, ok?). The computer doesn't turn on with the new RAM in - it
powers up, but the BIOS doesn't load, and the boot up process doesn't even
make it to the vaio/phoenix splash screen.

Any thoughts guys?  The BIOS is up to date and I have tried swapping out
only one memory unit at a time, and then tried swapping the memory ports and
all the other normal stuff... Someone on the ubuntu forums recommended that
I change the RAM's command rate to 2T, but I don't know how to do this and
fear that it means editing settings in the BIOS, because this computer's
BIOS is as change-resistant as could be imagined (there are no options to
change anything at all except the boot order and system time/date).

I don't want to think that I'm stuck with 2 bum units that I need to
return...