What's the difference between these processors? Just the higher clock speed?
Also, I heard that Intel is dropping the price on the Q9550 in August. Any truth to that?

The only difference between them is that the q9550's multiplier is higher by .5 (which shold give you about .2Ghz higher when overclocking)


Yes, it is almost certain that the q9950 will get a price drop on August 10. (just search google... too lazy to post links).