This type of question belongs in the Technical Q&A section of the site.
One of the hidden costs of upgrading to XP is the cost of replacing hardware devices. Many scanners and printers just don't work properly, or have drivers for XP.
Your older PlusTek scanner is one of these.
PlusTek specifically states that their driver will not work under XP.
http://www.plustek.com/download/9636t.htm
Since Windows 2000 is not listed as supported either, you may have just been lucky and the NT or Me driver worked for W2K.
You have 2 options:
Drop back to Windows 2000.
Buy a new scanner.
There are a number of advantages to having a USB port scanner over an EPP scanner.
Chas