If a BIOS update is available, it is usually a good idea to download & install it (check the tests done by this site when they retested the A7V133 with a BIOS update, it came 1st in most of the tests!!!)
Just make sure not to interrupt the BIOS update when in progress or U could well trash your motherboard bios completely...
Dunno about the 150Mhz memory, email Asus support and see what they say (some of those people do know a bit about their HW...) but DDR memory is a different size to normal SDRAM so it will not fit, it is designed for DDR boards only
Now where does this bit go ???