tell application "Startup Disk"Of course, change "OSXDisk" to the name of your disk containing OS X, and watch as I've broken the "set startup" line into two rows for easier display on the page -- enter it as one long row.
activate
set startup system folder alias to alias
"OSXDisk:System:Library:CoreServices:BootX"
quit
end tell
tell application "Finder"
restart
end tell
Why not just press the Option key when starting up to choose OS's to boot into? Because I have my ADB Wacom tablet, Kensington 4-button mouse and keyboard attached to my G4 with an iMate. I sure wish I had a similar AppleScript to change startup disks and restart when in OS X...

