yes, I had a 200gb maxtor hd that had an ATA card with it. then I took that out and put it on this computer. then it got messed up. i tried booting with linux CDs but nothing! it already has a 4gb hd. then I took out the battery from the mobo. now this.....
Ok for starters if im reading this correctly your trying to install a ATA controler and HD into this old computer that was working fine . This can be done but you have to zero out (erase data) on the Hard Drive reformat the Hard Drive then re-install the operating system . Now you said you allready have a 4 gig HD in it . Take out the ATA controler and new HD and see if it will boot and run from your old setup. If you want to switch to the ATA controler you will have to set up the old 4 gig HD and the new HD from scratch zero out reformat and re-install your Operating systems .
(zero out means erase all data on the HD , you can go to the Manufacturer website and download a utility that will run from a floppy to clear the HD off all data for a fresh install and format it as well )