John
I've got a freeware dvd to avi program, max 10 minutes per clip. So I convert dvd to .avi, then use Windows Movie maker within Win XP to convert this to a .wmv which is massively smaller without actually losing any quality. This can then go into your ppt presentation. Even the smallest resolution conversion looks good on the big screen. Works a treat, in fact have recently done a whole load of conversions for my USN colleagues at work. PM with an email address and I'll email you the set up file which is 1.32 mb.
Cheers
Oggin