HP Pavilion a712 XP desktop. I need this to copy over a number of 3.5 floppies unto CD or DVD. I have 2 EA Windows 95 units that are unusable to copy but the 3.5 drives seem to be o.k.! Not clear on the question at all...however a common thing on older floppy drives was the read unit would get mis-aligned over time...and floppy's that worked would no longer...
Buy a new floppy drive...not that expensive...and try to retrieve the data that way.
I'd buy an external USB Floppy Drive. I have one and it works awesome. On newer systems that support booting over USB you can even boot to DOS and perform BIOS flashing etc if needed.

They are cheap. I bought a Lacie External Floppy Drive about 5 years ago and keep it in a ziplock bag to keep dust out of it. Here is a cheap source for an external floppy drive.

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=-1&IsNodeId=1&Description=usb%20floppy&bop=And&Order=PRICE&PageSize=20

According to the age of your desktop, it probably has a floppy PORT on the motherboard, and should have a mini power plug for support of a single floppy drive, but I wouldnt use an old floppy drive out of old systems which can be dirty and could damage disks with important data, I'd got with the external USB floppy drive instead. I have use this external floppy drive with XP, Vista, and Windows 7 with no drivers having to be INSTALLED its pretty much plug-n-play.

Update: This link is to the motherboard that your system claims to have according to HP and it does have a FDD1 (floppy drive port) http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&docname=c00068983

So if you didnt want to spend any money you could move a floppy drive from an older system to this system using the floppy cable and drive from an older system, just be sure that its plugged in red or blue stripe to pin 1 etc ( most are keyed to only plug in the proper way however some older cables were not keyed and so it could be plugged in 180 degrees and not work ), and plug in the mini power jack from the Power Supply if you have one, most do. BUT I cant find any info on if there is a knock out to add a 3.5" floppy drive so you may have to do this with the cover open and use the floppy drive on a temporary basis. Just be sure that the floppy drive doesnt fall into the case if on its SIDE and short the motherboard etc.

The BIOS should autodetect the floppy drive, however if it doesnt its easy to enable Floppy A: 3.5" 1.44MB assuming the drive is a 1.44MB drive and not an older 720K drive.