What kind of polarzing filter should I use with my digital rebel XT?

Question:

What kind of polarzing filter should I use with my digital rebel XT?

Best Answer - Chosen by Asker: There is two types of polarizing filters,
1- Circular polarizers are specifically designed for use with auto-focus SLR cameras and
2-Linear polarizers are used with most manual focus cameras and are not recommended for auto-focus cameras.

Are you using 17-85mm ? ( the ring must be 67mm) many brands are avaiable on market.