Basic question about configuring an AMD system

[anyuser]

I'm building a new computer and I plan on using the kt133A chipset and running a FSB of 133 with pc133 CAS2 RAM. My question is concerns references I here about T-birds that "are able to make use of the 133 FSB". What is the distinction between T-birds which can and cannot make use of a FSB 133? How high up the mhz do I have to go? I was planning on a 850-900 mhz CPU. If it turns out I can't afford a CPU that's compatible with a FSB 133 do I have to step down to a kt133 and FSB of 100? If that's so I'll just wait for kt266.