Progressive Scan versus Interlaced

Question

OK I understand the whole principal behind Progressive Scan but I have yet to be able to see a difference! I have had 3 different Progressive Scan players hooked up to my TV and a Standard Player and have switched between them to try to find the difference visually! What gives? To answer a few questions I'll give you a rundown of the equiptment: Panasonic PT-53WX42 53" HDTV Rear Projection (Digital Scan Rate 1080i, 480p) Venturer HTIB -not Progressive Scan- S-Video Input Panasonic -Progressive Scan- Component Input Samsung DT-150 -Progressive Scan- Component Input Samsung HT-DL200P-Progressive Scan- Component Input Are they're certain DVD's that you can tell more of a difference on? Thanks for your time!