I have an asus P2B-F mobo running 512 megs of ram It's capible of holding a gig of ram. It has a PIII-450mhz with a 100mhz fsb thus I need PC-100 but for stick of 256 its like a 100 dollars. where as like pc2700 for stick of 512 its like 50 bucks. whats the deal? why is PC100 so expensive?

I Hate to say this but this is a typical trend that I've seen before. I believe it has to do with the fact that this type of RAM isn't manufactured anymore or if it is, it's made in limited amounts and hence the price goes up at the retail end. :evil:

You may be able to get away with pc 133 RAM as it can often be used on a 100 Mhz bus. (Your bus will run as fast as the slowest memory chip will let it.)

I have to admit that, a notebook may have differences that I'm not aware of as I have never owned one, however the theroy worked with my Pentium II - 266 that had a 66 Mhz bus and had a total of 352 Mb of memory installed including a 256 mb pc 133 DIMM.

I agree with The Soundman. I have a P11 400Mhz 100 fsb and I use PC133 memory. I have not had any problems. Also check around for pricing. I just got a Tigerdirect catalog and the prices are around $50 for 256MB. Check with friends, family, or school to see if anyone is getting rid of their old computers. That is how I usually come by my older RAM.