best ram 4 the Asus K8V Deluxe mobo?
Not to be rude or anything, but have you tried looking at the board on Asus' product pages?
But I'll be nice and tell you that DDR400 is the best ram you can use. You can have 3 sticks of it, and a maximum of 3GB.
Don't buy anything from Crucial.
Stick with the decent performance memory manufactors like Corsair, OCZ, Mushkin etc.
And get lots - the more the merrier
Crucial is a very good brand & a lot of people on these forums use them. They're not much into the "extreme performance" scene but have introduced their ballistix series to try & catch up with the Corsair & Kingston brands. They have a lifetime warranty so you can't go wrong by choosing them.
As for the best ram for your board, it all depends on what you intend to do with it. We can't recommend the same things if you're into overclcoking or not, etc.
I'm using that board with the 64-bit 3200+ and am using the Kingston memory that's recommended on Asus' website (as per Mr. G's instructions). The system's rock solid. Running 2 x 512 for a full Gig. Hope that helps a little.