see wht i can understand is , u r having 2 hdd's one 80 gb and one 20 gb . and both of them are not getting detected. i suggest u try the following,

connect your new 80 gb hdd as primary master. check the jumper settings correctly and make it a master.

connect the power cable (molex) properly and also the ide connector firmly.

your problem seems more of a RAM problem to me .. so try replacing ur ram n see.