You need the Converter Patch available for Download from M$ here
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=ec563dee-6bfb-431d-b39e-2d672c0c223f
Just install this patch and Word will open the documents and convert as required. As said above if there is a lot of Fields in the formating of the WP Document Word will not do a perfect job at converting to the Doc or DocX format but it will convert the majority of the document so that you can repair any problems.
Failing that if you still have Word Perfect installed you can open each document in WP and save it as a Word Document.
If you no longer are using Word Perfect and do not have it installed you can download the Trial Version of WP Office X5 from Corel here and install it then use it to convert to the Doc Format. Though you'll need to register to get the trial version of the current version of WP Office.
http://www.corel.com/servlet/Satellite/us/en/Product/1208530086166
Probably a better idea is to just continue using Coral's Word Perfect Office as it has better features and is easier to use than M$ Office. The current version X5 will also save as PDF Files if required to make your Documents truly Portable and able to be read across all platforms. I know the people working for me ridiculed me for still using WP and now they prefer it to M$ Office and constantly complain about needing to use M$ Office when they are away from their Work systems or using a customers system and showing how to do something in Word.
Failing that you can always use Open Office 3 which is also free from here
http://download.openoffice.org/
Using any of the above will allow you to perform the conversions and you'll not need to pay anyone anything to do them if you still need to anyway. ;)
Col