Need some advice on memory upgrade

I was thinking about picking up a 256mb PC133 SDRAM stick I saw on sale this week at "Bestbuy". Does anyone know if it'll be fully compatible with the 4K? Also does it make a difference in the 4K if one memory module installed is PC100 and the other PC133? If it does, how can I found out what type the one currently installed in my 4K is? Thanks.

Both pc 100 and pc133 are compatible so it should not make a differnce if both. Just make sure it is a CL2.