I recently bought a 4600 ht with the 800mhz fsb, which should arrive in a few days!!. I bought this online using the customize selections. As far as RAM goes it only offerd me the pc2700 (333mhz) type of memory. I wanted to choose the pc3200 (400mhz), but it never gave me that option. My questions are: 1. How much slower will my pc work? 2. Will my bus speed be now 666mhz instead of 800mhz? Can I add a pair of pc3200 ram later on without any conflicts?

if u use different speed RAM u may/will experience problems. if u are going to upgrade your RAM i would only put the new chips in and leave out the slower RAM. (maybe use it for a paperweight?)
:)

btw there is RAM out there that is FASTER than 400mhz . . .