Welcome Jon!
Proshow Producer 4.5 can output the slideslow as a video file. If you choose to make an MPEG-2 file, DVD Architect 5 will be able to use it directly without having to encode and/or recompress. Proshow Producer has two presets for making an MPEG-2 file: DVD which will produce standard definition MPEG-2 suitable for making DVDs, and HD which will will produce High Definition MPEG-2 suitable for making Blu-ray disks. You can also set the video properties using the custom option. For details, see the manual:
http://files.photodex.com/docs/manuals/ProShowProducer45.pdf. The information on how to create a video file begins in chapter 17 page 380. And, the presets are described on page 383.