I've got a file in wmv form but it's quite large (600MB). I've been told Photoshop can compress it - are there any other freeware or reliable software that's not as expensive that someone can suggest for me please?
Any free video conversion software should convert that to an mp4 file that is not so large. Divx may well not. Photoshop .. along with other image editing suites, probably compress highly to add into slideshows, presentations, etc.
You would be best compressing with a standalone sofware.