its a series code name. the 2800 is not 2.8 ghz, its much less. but amd cpus have higher cycles per minute, making thei cpus more powerfull. also, because of the 64bit, but there are no 64bit programs, and few os taht arre 64 bit
whats ur budget? amd has released 939 socket proc for most of there 64s. they have it is 3000,3200, 3500. dont get the 754 soct. it doesnt support dual channel, and now its same price as the 939s.