Some people have had to manually build hard drives of 80 gb or greater on mk II units. Pretty much any drive should work just fine some sites have 80 gb units for around ~ 115 usd .

Check the ide cable and header to look for damage. Be careful taking the connector on and off a drive. If you can find some of those little red washers use them inbetween the screw and drive mounting. Dont overtighten anything.