We stayed at Star Island last year 2003 for Spring Break. I'm sorry but I don't believe they have Disney transportation but I could be wrong. We used rental car. We were staying there courtesy of DBIL/DSIL in a very nice 3 Bedroom villa. Wonderful resort if you don't mind being off-site. We have since become DVC owners at Beach Club Villas because even though it was a very relaxing resort, we just missed the "magic" of WDW.
Have a great time. Awesome pools and fun activities for the whole family!