Access definitely, more scalable and better designed for multiple use/ edit - Jet 4.0 it much better than Excel. Also 600 students doesn't necessarily mean 600 rows! Could include courses or other details which would require one to many. In that case it would scale very rapidly. Ive seen so many people use Excel as a database and unless you are very savvy and can link in forms and events it very rarely (if ever) works. One of the reasons is its not efficient to manage many columns of data, you need it in a GUI somehow.
2 hour tutorial on simple database design and you can put together some very basic Access database.