yeah, from what you are seem to be asking, you aren't getting the fsb to 133 but just pc133 ram, which is fine for VIA socketa mobo.
[edit] just saw your sig. its a duron, which means it a VIA board. plus its a socketA (why am i think thinking AMD750 for socketa? sheesh), fsb to 133 is prob not gonna happen but pc133 ram is a go. But if you stick in pc133 with the pc100 you already have, its prob gonna run at pc100.