"Invalid Partition Table" - HELP !!!!

[Mr Flibble]

Start at the beginning.
Yesterday, my comp would not boot up. Then after a number of tries, I tried a "restore" that comes with my computer when bought. Only this time, it doesnt. For the first time, despite running the whole thing, I get - "Hard Drive Error" so, as my warranty is up, (I did try all the same) I took out the snuffed HD, and moved up my second HD to put my WinXP Home onto. Only it WONT install. I put another smaller HD on to take up the cause, and it asked whether I wanted to partition it, OK I said, only it got through the full 100% (taking 3 hours plus for a 30 gig) and then said it couldn't format as it may be corrupted/damaged (which it isnt as it had been working fine in my sons old comp) So I am baffled as to what to do next. Aha ! I thought. I'll use the western digital "data lifeguard" as they are both WD. It refuses to run the floppy at all. "Invalid Partition Table" is all I get when I try to run the floppy. I change the bios for only floppy boot up and it will not run. Same again - "Invalid Partition Table" so I cant even format the HD's I have left. I have another HD ordered and if it goes the same route I'll be in the same mess. Could anyone shed any light ?
(This is being done on my sons computer)