Sorry I took an earlier awnser as to you knew this.

Anyway HP's site does not help much.

Basically you want to remove the battery from the motherboard & some boards have jumpers to short as well. After you do this & can enter the BIOS setup you will need to reset your date & time.

You would need to open the case (making sure that you are properly grounded) & locate the battery. A flat disk like camera/ watch battery.
Remove the battery for a few minutes & then replace. If there is a 3 pin jumper in the same vacinity perhaps labled CMOS it will have a plastic sleeve covering say pin 1&2. This would be moved to cover pins 2&3 (with the battery out) in order to short/reset the CMOS.

Sorry I can't be more specific. These are the basics & the HP site does not help much. I also have an old HP & just removing the battery is the only option on my board.

Beyond this getting a floppy to boot would be the next step.

This will help you with the bios clearing, setup, etc.

i tried switching out the battery with a new one but that didnt do anything. i didnt see any jumper pins or anything that looked like what you described.

Can you go back to the last hardware configuration that worked?

You mentioned that before switching hard drives things were ok?

Can you go back there?

My only other idea is to get a floppy to boot.

Either a BIOS upgrade or a Hard Drive Diagnostic.
Do you know the make of the hard drive?
There is a general list of manufacturers here:
http://www.tacktech.com/display.cfm?ttid=287

Did you have a bootable floppy that you put the BIOS on? (post #9)

Also have you checked the previous links such as:

http://h10025.www1.hp.com/ewfrf/wc/d...cname=bph07119

i tried the boot disk but it didnt help. im trying t upgrade my main pc thats why i was switching the hard drives.

At this point the only thing I can think of is that the original hard drive contained essential BIOS information.

Have you tried replacing the original hard drive just to see if you can at least enter the BIOS setup?