Zulran,

If the old computer had a different operating system perhaps an updated driver from here will solve the problem.

Do you have or did you download the Windows XP drivers from HP?  You must have the Windows XP drivers, old Win98/Me drivers are incompatible with XP.  And, the correct install procedure is to run the HP installation program and ONLY connect the unit to the PC when the installation program tells you to.  If you connect the unit first, either Windows will install incorrect drivers or it will fail because Windows could not find any drivers. 

So if HP isn't offer a driver what should I do?

I had windows xp pro on the old computer, I have xp media center on the new one.....

Windows x64 isn't xp pro media center is it?

No, they are two different products.

http://www.microsoft.com/windows/default.mspx

If you have XP 64, you are limited as many vendors are not supporting 64 yet, or not supporting 64 for discontinued models such as you have.  About the only option is to try and find a new printer that is 64 compatible or go back to the supported Windows XP.