Old Hard drive,

My Old hard drive waas getting to full. So I put a biger one in. No problems, but in deciding to use my old hard drive as a external drive, each time I try to access it the ol XP trys torun and maks a mess and will not act as a external hard drive. I can replace it in the computer but if I try to delte it it "is in use " and will not delete it. any ideas on how to delete the old drive XP so I may use it as a external drive? Thanks.

Is there anything on it that you need to save? If not, I would put it in the machine by itself and boot it up with a Win98 boot disk and fdisk / format it.