Is PC133 RAM backwards compatible w/ a PC66 mobo?

The 'rents have a 400mhz Celeron Gateway with 64MB of RAM.

I need to upgrade it so my Dad can use the new slide scanner he just bought. Crucial says it takes PC66, which is impossible to find cheap these days.

Is 168 pin PC133 backwarks compatible with PC66 like it is with PC100?

Thanks.

Oh, and this mobo only takes up to 256MB! WTF?

It should work, however, I hesitate to say it will for sure. There’s a lot of proprietary stuff around (Compaq is particularly bad with this), and not all RAM/mainboard combinations will play nice together. Many sites that sell RAM will have a compatibility chart, so you can see what memory will work in your particular mainboard. These are rarely comprehensive, though, so your best bet, really, is to with whatever Gateway recommends.