yep.
PC2100 = 266 FSB
PC2700 = 333 FSB
PC3200 = 400 FSB
Installing slower RAM can be done, but it will be a botteneck. Installing faster RAM can also be done, but won't increase performance any. i would only go with faster RAM if you are planning an upgrade in the future that will allow you to take advantage of it.
Welcome to AT forums, btw...
