Katpadi is the train station closest to Vellore (about 7km from CMC). Click on the map for a more detailed view. Ooty (where I went last weekend) is in the most westerly part of Tamil Nadu. This weekend I will be heading to Bangalore on the train (west of here) and weekend 3 will potentially be a trip down to Madurai (about where the 78E and 10N lines intersect) and Trichy.
So there you go. Click clunk.