Use VLC
http://www.videolan.org/vlc/It is a very good alternative to WMP11 and very popular.
I missed that your HDD Died. If it had not and you needed to access your recovery partition to reinstall your original software you could have done it by following the directions provided here:
http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&dlc=en&cc=us&product=437888&docname=bph07142You could try calling HP/Compaq and get them to send you recovery media that you could use to reinstall the software.
You can check if your PC is still under warranty here:
http://h10025.www1.hp.com/ewfrf/wc/weInput?lc=en&dlc=en&cc=usYou could get them to send you a new HDD and a Recovery CD if it is still under warranty.
If it is out of warranty then your best bet is just to purchase the full version of PowerDVD 10, try the codec pac suggested above or use VLC.